What Caffeine Actually Does to Your Brain

For all of its wild popularity, caffeine is one seriously misunderstood substance. It's not a simple upper, and it works differently on different people with different tolerances—even in different menstrual cycles. But you can make it work better for you.
Photo by rbrwr.
We've covered all kinds of caffeine "hacks" here at Lifehacker, from taking "caffeine naps" to getting "optimally wired." And, of course, we're obsessed with the perfect cup of coffee. But when it comes to why so many of us love our coffee, tea, soda, or energy drink fixes, and what they actually do to our busy brains, we've never really dug in.
While there's a whole lot one can read on caffeine, most of it falls in the realm of highly specific medical research, or often conflicting anecdotal evidence. Luckily, one intrepid reader and writer has actually done that reading, and weighed that evidence, and put together a highly readable treatise on the subject. Buzz: The Science and Lore of Alcohol and Caffeine, by Stephen R. Braun, is well worth the short 224-page read. It was released in 1997, but remains the most accessible treatise on what is and isn't understood about what caffeine and alcohol do to the brain. It's not a social history of coffee, or a lecture on the evils of mass-market soda—it's condensed but clean science.
What follows is a brief explainer on how caffeine affects productivity, drawn from Buzz and other sources noted at bottom. We also sent Braun a few of the questions that arose while reading, and he graciously agreed to answer them.

Caffeine Doesn't Actually Get You Wired

Right off the bat, it's worth stating again: the human brain, and caffeine, are nowhere near totally understood and easily explained by modern science. That said, there is a consensus on how a compound found all over nature, caffeine, affects the mind.
Every moment that you're awake, the neurons in your brain are firing away. As those neurons fire, they produce adenosine as a byproduct, but adenosine is far from excrement. Your nervous system is actively monitoring adenosine levels through receptors. Normally, when adenosine levels reach a certain point in your brain and spinal cord, your body will start nudging you toward sleep, or at least taking it easy. There are actually a few different adenosine receptors throughout the body, but the one caffeine seems to interact with most directly is the A1 receptor. More on that later.
Enter caffeine. It occurs in all kinds of plants, and chemical relatives of caffeine are found in your own body. But taken in substantial amounts—the semi-standard 100mg that comes from a strong eight-ounce coffee, for instance—it functions as a supremely talented adenosine impersonator. It heads right for the adenosine receptors in your system and, because of its similarities to adenosine, it's accepted by your body as the real thing and gets into the receptors.
Update: Commenter dangermou5e reminds us of web comic The Oatmeal's take on adenosine and caffeine. It's concise:

More important than just fitting in, though, caffeine actually binds to those receptors in efficient fashion, but doesn't activate them—they're plugged up by caffeine's unique shape and chemical makeup. With those receptors blocked, the brain's own stimulants, dopamine and glutamate, can do their work more freely—"Like taking the chaperones out of a high school dance," Braun writes in an email. In the book, he ultimately likens caffeine's powers to "putting a block of wood under one of the brain's primary brake pedals."
It's an apt metaphor, because it spells out that caffeine very clearly doesn't press the "gas" on your brain, and that it only blocks a "primary" brake. There are other compounds and receptors that have an effect on what your energy levels feel like—GABA, for example—but caffeine is a crude way of preventing your brain from bringing things to a halt. "You can," Braun writes, "get wired only to the extent that your natural excitatory neurotransmitters support it." In other words, you can't use caffeine to completely wipe out an entire week's worth of very late nights of studying, but you can use it to make yourself feel less bogged down by sleepy feelings in the morning.
These effects will vary, in length and strength of effect, from person to person, depending on genetics, other physiology factors, and tolerance. But more on that in a bit. What's important to take away is that caffeine is not as simple in effect as a direct stimulant, such as amphetamines or cocaine; its effect on your alertness is far more subtle.

It Boosts Your Speed, But Not Your Skill—Depending on Your Skill Set

Johann Sebastian Bach loved him some coffee. So did Voltaire, Balzac, and many other great minds. But the type of work they did didn't necessarily get a boost from their prodigious coffee consumption—unless their work was so second-nature to them that it felt like data entry.
The general consensus on caffeine studies shows that it can enhance work output, but mainly in certain types of work. For tired people who are doing work that's relatively straightforward, that doesn't require lots of subtle or abstract thinking, coffee has been shown to help increase output and quality. Caffeine has also been seen to improve memory creation and retention when it comes to "declarative memory," the kind students use to remember lists or answers to exam questions.
(In a semi-crazy side note we couldn't resist, researchers have implied this memory boost may be tied to caffeine's effect on adrenaline production. You have, presumably, sharper memories of terrifying or exhilarating moments in life, due in part to your body's fight-or-flight juice. Everyone has their "Where I was when I heard that X died" story, plugging in John F. Kennedy, John Lennon, or Kurt Cobain, depending on generational relatability).
Then again, one study in which subjects proofread text showed that a measurable boost was mainly seen by those who could be considered "impulsive," or willing to sacrifice accuracy and quality for speed. And the effect was only seen in morning tests, indicating the subjects may have either become lightly dependent on caffeine, or were more disposed to such tasks at that time of day.
So when it comes to caffeine's effects on your work, think speed, not power. Or consider it an unresolved question. If we're only part of the way to understanding how caffeine affects the brain, we're a long way to knowing exactly what kind of chemicals or processes are affected when, say, one writes a post about caffeine science one highly caffeinated afternoon.
For a more direct look at what happens to your brain when there's caffeine in your system, we turn to the the crew at Current. They hooked up one of their reporters to a brain monitor while taking on some new caffeine habits, and share their brains on caffeine:

Effectiveness, Tolerance, and Headaches

Why do so many patients coming out of anesthesia after major surgery feel a headache? It's because, in most cases, they're not used to going so long without coffee. The good news? If they wait a few more days, they can start saving coffee again for when they really need it.
The effectiveness of caffeine varies significantly from person to person, due to genetics and other factors in play. The average half-life of caffeine—that is, how long it takes for half of an ingested dose to wear off—is about five to six hours in a human body. Women taking oral birth control require about twice as long to process caffeine. Women between the ovulation and beginning of menstruation see a similar, if less severe, extended half-life. For regular smokers, caffeine takes half as long to process—which, in some ways, explains why smokers often drink more coffee and feel more agitated and anxious, because they're unaware of how their bodies work without cigarettes.
As one starts to regularly take in caffeine, the body and mind build up a tolerance to it, so getting the same kind of boost as one's first-ever sip takes more caffeine—this, researchers can agree on. Exactly how that tolerance develops is not so clear. Many studies have suggested that, just as with any drug addiction, the brain strives to return to its normal function while under "attack" from caffeine by up-regulating, or creating more adenosine receptors. But regular caffeine use has also been shown to decrease receptors for norepinephrine, a hormone akin to adrenaline, along with serotonin, a mood enhancer. At the same time, your body can see a 65 percent increase in receptors for GABA, a compound that does many things, including regulate muscle tone and neuron firing. Some studies have also seen changes in different adenosine receptors when caffeine becomes a regular thing.
Caffeine, it's been suggested, is probably not directly responsible for all these changes. By keeping your brain from using its normal "I'm tired" sensors, though, your caffeine may be causing the brain to change the way all of its generally excitable things are regulated. Your next venti double shot goes a little less far each time, in any case. Photo by zoghal.
A 1995 study suggests that humans become tolerant to their daily dose of caffeine—whether a single soda or a serious espresso habit—somewhere between a week and 12 days. And that tolerance is pretty strong. One test of regular caffeine pill use had some participants getting an astronomical 900 milligrams per day, others placebos—found that the two groups were nearly identical in mood, energy, and alertness after 18 days. The folks taking the equivalent of nine stiff coffee pours every day weren't really feeling it anymore. They would feel it, though, when they stopped.
You start to feel caffeine withdrawal very quickly, anywhere from 12 to 24 hours after your last use. That's a big part of why that first cup or can in the morning is so important—it's staving off the early effects of withdrawal. The reasons for the withdrawal are the same as with any substance dependency: your brain was used to operating one way with caffeine, and now it's suddenly working under completely different circumstances, but all those receptor changes are still in place. Headaches are the nearly universal effect of cutting off caffeine, but depression, fatigue, lethargy, irritability, nausea, and vomiting can be part of your cut-off, too, along with more specific issues, like eye muscle spasms. Generally, though, you'll be over it in around 10 days—again, depending on your own physiology and other factors.
Update: Commenter microinjectionist offers his own summary of more recent caffeine studies, which offers expanded reasons why caffeine users feel a "morning crash," as well as why your whole body, not just your brain, might feel so bad when you withdraw.

Getting Out of the Habit and Learning to Tame Caffeine

Beyond the equivalent of four cups of coffee in your system at once, caffeine isn't giving you much more boost—in fact, at around the ten-cup level, you're probably less alert than non-drinkers. So what if you want to start getting a real boost from caffeine once again, in a newly-learned, less-dependent way?
Our own Jason Fitzpatrick has both intentionally "quit" caffeine, as well as just plain run out of coffee. Being the kind of guy who measures his own headaches and discomfort, he suggests measuring your caffeine intake, using caffeine amounts in all your drinks, chocolate, and other "boosting" foods. Wise Bread has a good roundup of caffeine amounts, and the Buzz Vs. The Bulge chart also shows how many calories you'll be cutting if you start scaling back. Once you know your levels, map out a multi-week process of scaling down, and stick to it. Jason also suggests that dependency kicking is a good time to start taking walks, doing breathing exercises, or other mind-clearing things, because, in his experience, their effects are much greater when caffeine is not so much a part of your make-up.
Braun, author of Buzz, sees it the same way, but still uses coffee—strategically, according to our email exchange:

In practical terms, this means that if you'd like to be able to turn to caffeine when you need it for a quick, effective jolt, it's best to let your brain "dry out" for at least several days prior to administration. This is actually my current mode of consumption. I don't regularly drink coffee anymore (gasp).
This from a man who loved (and wore out) his home espresso maker. I love coffee in all its guises. But after 30+ years it wasn't working for me. For one thing, the problem with caffeine is that there are adenosine receptors all over the body, including muscles. For me, that meant that caffeine made me vaguely stiff and sore, and it aggravated a tender lower back that was prone to spasm. But I also just wasn't getting a clean, clear buzz from coffee...I drank so much, so regularly, that drinking an extra cup or two didn't do a helluva lot except, perhaps, make me a little more irritable.
So about a year ago I slowly tapered down, and now I have, if anything, a cup of tea (half black, half peppermint) in the morning. (The amount of caffeine from the black tea isn't enough to wire a gnat.) Not only does my body feel better now, my brain is clean of caffeine, so I really want (or need) a good neural jump-start, I will freely...nay, ecstatically...indulge. Then I stop and let the brain settle again.
That's the theory, anyway...and it's basically true, although I'll freely admit that sometimes I have an espresso or coffee just because it tastes so damned good.

If you'd like Braun's extended takes on caffeine tolerance and withdrawal, along with the advent of energy drinks and caffeine's impact on creativity, you can read our full email interview.

The Human Body - A Dissection (Not for Weak Hearted People)

From the tiniest veins, arteries and nerves to serial cross-sections of the spinal cord, these incredibly detailed dissections show and label most every part of the human body.

The collection is the product of a 17-year collaboration between David L. Bassett, a School of Medicine alumnus and faculty member known for his elegant dissections and love for the human body, and William Gruber, the photographer who invented the View-Master stereoscopic viewing device.

The partnership between the two resulted in the production of the
Stereoscopic Atlas of Human Anatomy, which began in 1948, but was not not completed until 1962. It consisted of 221 View-Master reels with 1,554 color stereo views of dissections of every body region. Each stereo view was accompanied by a black-and-white, labeled drawing and explanatory text.

A courtesy the Lane Medical Archives (thanks Drew!), today we present you some of the most impressive pictures of The Basset Collection. Meet the Human Body.


A deep dissection of the side of the head shows the many blood vessels (red arteries, blue veins) and nerves (graying white) in the facial region. The hole is the external ear canal. The temporal muscle, used for chewing, is the prominent fan shaped muscle on the side of skull, behind the mouth and above the jaw.


After the removal of an outer layer of bones around the jaw, the dissection shows blood vessels and sensory nerves to the lower teeth and chin.


The onion-like structure is an eye, seen from above with the bony roof of the eye socket removed. The profusion of blood vessels and the muscles that rotate the eye are visible.


A pelvis from a woman, right, is lighter and wider than that of a man, left. The wider angle of a woman's pubic bones at the base of the pelvis allows birthing of a baby.


Removal of the skin and the layer of tough tissue beneath it, the palmar fascia, reveals a complex arrangement of blood vessels and nerves in the hand and wrist.


This dissection of the kidneys was done after red latex was injected into the arteries and blue latex into the veins.


With all layers of the skin removed on the left side of the head and neck, the dissection displays the blood vessels and nerves of the scalp, almost all of which come from the periphery, not through the skull. Colored latex was injected into the blood vessels: red for arteries, blue for veins. The structures in the neck remain covered by a tough layer of tissue known as the cervical fascia.


Inside the vertebral column, cut in half vertically, is a channel for the spinal nerves. The brown material is the bones; the white material is the intervertral disks that sometimes "rupture," causing back pain. A horizontal split has been made on the left to show the connection of the sacrum, a triangular bone at the base of the spine, to the pelvis.


This view of the wrist joint features the two rows of four carpal bones each and shows how they are connected to the bones of the forearm and the fingers.


A dissection of the leg and the foot displays the long tendons connected to the toes, and the blood vessels and nerves to the top of the foot.


This dissection of the backbone was performed by Donald Stilwell, another Stanford professor, for the Bassett atlas. Note the profusion of arterial blood vessels nourishing the vertebral area of the neck and chest area. Also, at the top, the ends of the vertebral arteries, which pass into the skull to nourish the brain.


The mediastinum, a central chest compartment located between the lungs, houses the heart. Immediately to the right of the heart is the aorta, the largest artery of the body. To the right of the aorta are groups of blood vessels (one artery and two companion veins) that run between the ribs to distribute blood through the body. The phrenic nerve, which sends messages to the diaphragm to breath, is visible as it crosses the heart vertically.


Dissection of the meninges and brain in situ. On the right the calvaria and layers of the scalp are shown in relation to the dura. On the left the dura has been cut away to reveal the cerebral hemisphere and cerebellum covered with the arachnoid membrane. The confluence of the sinuses is shown.


The sclera and cornea have been cut away on the medial side of a right eye to display the anterior chamber, iris, ciliary body and outer surface of the choroid. Although none of the vessels has been injected, the branches of the superior and inferior medial vorticose veins are clearly visible. The long posterior ciliary artery was cut across in the resection of the sclera but its course can be traced nearly to the ciliary body.


On this dissection of the heart, the epicardium has been removed from all parts of the atria with the exception of the left auricle.


Dissection of lungs in situ. The lungs have been dissected from their medial surfaces and are reflected laterally for this image. Fragmentary portions of all of the chambers of the heart have been preserved. The great vessels have been kept intact, although the aorta and pulmonary trunk have been elevated to expose more posterior parts of the heart.


The cervical spinal cord. By removing the rear arches of the neck (cervical) vertebra and the fibrous covering (dura) over the spinal cord one sees the cervical spinal cord and its nerves. The blood vessels nourishing the cord and vertebral column and the origin of the cord from the brain are clearly shown.


Dissection of thorax from a posterior approach. Ribs and vertebral bodies have been resected bilaterally between the second and the ninth thoracic segments. The periosteum which covered the inner surfaces of the ribs have been preserved in most areas. The anterior longitudinal ligament, with remnants of the intervertebral discs attached, has also been retained in part. The lungs have been inflated and are visible through the intact costal pleura. The proximal parts of the III-VII spinal nerves have been positioned on the pleura in such a way that their dorsal and ventral roots, dorsal rami and communications with the sympathetic trunks are visible. These components are labeled for the left seventh thoracic nerve. The intercostal arteries and veins have been cut off in various ways.


The knee joint opened from the front shows the inner surface of the knee cap or patella within its large ligament which is folded downward and forward. The ear shaped cartilages lie on the surface of the joint floor formed by the tibia. Between the cartilages one sees the cut ends of the cruciate ligaments so often injured in athletics and frequently reconstructed surgically.


The Jawbone. The masseter muscle of mastication reflected back to expose the jawbone (mandible) and the related vessels, nerves and muscles.

Sodium ions could one day let you grow a new hand

A new cocktail that allows sodium ions to pour into cells makes tadpoles grow new tails. A similar one could be used to regenerate human spinal cords and lost limbs.
It's clearly possible to grow muscle tissue, nerves, and organs. We all did it once. We should be able to do it again. For some reason, though, we can't. After a certain stage of life, or after certain injuries, tissues scab over instead of growing anew. The exact reason why they do this has puzzled many. Now one solution may have been found by researchers at Tufts University: not enought sodium ions.
One hour of exposure to a drug cocktail which makes sodium ions pour into cells has caused tadpoles to regrow their tails (as in the image above). These are not dummy tails, like those grown by certain lizards after they lose their tails to predators. The new tadpole tails have muscle and spinal cords, just like regular tails.
Professor Michael Levin of Tufts is looking at the long-term applications of such a find:

We have significantly extended the effective treatment window, demonstrating that even after scar-like wound covering begins to form, control of physiological signals can still induce regeneration. Artificially causing an influx of sodium for just one hour can overcome a variety of problems, such as the decline in regenerative ability that comes with age and the effect of regeneration-blocking drugs.

In other words, this can help people who have been undergone chemotherapy and loss of limbs. And, of course, this is the newest idea that can make people immortal. Its most immediate possibilities, though, lie in spinal cord regeneration. Since tadpoles build tissue, including spinal cords, like people do, this could be a possible treatment for those with spinal cord injuries.
Via Tufts and the Journal of Neuroscience. Image via Tufts.

anatomical maps

'de formato foetu' 1631 by giulio casserio (ca. 1552-1616), anatomist and odoardo fialetti, artist courtesy the national library of medicine 'anatomia del corpo humano' - rome, 1559 by juan valverde de amusco (ca. 1525 - ca. 1588), anatomist 'anatomia del corpo humano' - rome, 1559 by juan valverde de amusco (ca. 1525 - ca. 1588), anatomist 'tabulae anatomicae' - venice, 1627 by giulio casserio (ca. 1552-1616), anatomist and odoardo fialetti, artist 'de humanicorporis fabrica' - andreas vesalius (1514-1564) 'de humanicorporis fabrica' - andreas vesalius (1514-1564)

Anatomy of Japanese folk monsters

Yōkai Daizukai, an illustrated guide to yōkai authored by manga artist Shigeru Mizuki, features a collection of cutaway diagrams showing the anatomy of 85 traditional monsters from Japanese folklore (which also appear in Mizuki's GeGeGe no Kitarō anime/manga). Here are a few illustrations from the book.

Kuro-kamikiri [+]

The Kuro-kamikiri ("black hair cutter") is a large, black-haired creature that sneaks up on women in the street at night and surreptitiously cuts off their hair. Anatomical features include a brain wired for stealth and trickery, razor-sharp claws, a long, coiling tongue covered in tiny hair-grabbing spines, and a sac for storing sleeping powder used to knock out victims. The digestive system includes an organ that produces a hair-dissolving fluid, as well as an organ with finger-like projections that thump the sides of the intestines to aid digestion.

Makura-gaeshi [+]

The Makura-gaeshi ("pillow-mover") is a soul-stealing prankster known for moving pillows around while people sleep. The creature is invisible to adults and can only be seen by children. Anatomical features include an organ for storing souls stolen from children, another for converting the souls to energy and supplying it to the rest of the body, and a pouch containing magical sand that puts people to sleep when it gets in the eyes. In addition, the monster has two brains -- one for devising pranks, and one for creating rainbow-colored light that it emits through its eyes.

Doro-ta-bō [+]

The Doro-ta-bō ("muddy rice field man"), a monster found in muddy rice fields, is said to be the restless spirit of a hard-working farmer whose lazy son sold his land after he died. The monster is often heard yelling, "Give me back my rice field!" Anatomical features include a gelatinous lower body that merges into the earth, a 'mud sac' that draws nourishment from the soil, lungs that allow the creature to breathe when buried, and an organ that converts the Doro-ta-bō's resentment into energy that heats up his muddy spit. One eyeball remains hidden under the skin until the monster encounters the owner of the rice field, at which time the eye emerges and emits a strange, disorienting light.

Hyōsube [+]

The Hyōsube, a child-sized river monster (a relative of the kappa) from Kyushu that lives in underwater caves, ventures onto land at night to eat rice plants. The monster has a relatively small brain, a nervous system specialized in detecting the presence of humans, thick rubbery skin, sharp claws, two small stomachs (one for rice grains and one for fish), a large sac for storing surplus food, and two large oxygen sacs for emergency use. A pair of rotating bone coils produce an illness-inducing bacteria that the monster sprinkles on unsuspecting humans.

Yanagi-baba [+]

Yanagi-baba ("willow witch") is the spirit of 1,000-year-old willow tree. Anatomical features include long, green hair resembling leafy willow branches, wrinkled bark-like skin, a stomach that supplies nourishment directly to the tree roots, a sac for storing tree sap, and a cane cut from the wood of the old tree. Although Yanagi-baba is relatively harmless, she is known to harass passersby by snatching umbrellas into her hair, blowing fog out through her nose, and spitting tree sap.

Mannen-dake [+]

The Mannen-dake ("10,000-year bamboo") is a bamboo-like monster that feeds on the souls of lost travelers camping in the woods. Anatomical features include a series of tubes that produce air that causes travelers to lose their way, syringe-like fingers the monster inserts into victims to suck out their souls, and a sac that holds the stolen souls.

Fukuro-sage [+]

The Fukuro-sage -- a type of tanuki (raccoon dog) found in Nagano prefecture and Shikoku -- has the ability to shapeshift into a sake bottle, which is typically seen rolling down sloping streets. The bottle may pose a danger to people who try to follow it downhill, as it may lead them off a cliff or into a ditch. The Fukuro-sage usually wears a large potato leaf or fern leaf on its head and carries a bag made from human skin. The bag contains a bottle of poison sake. Anatomical features include a stomach that turns food into sake, a sac for storing poison that it mixes into drinks, and a pouch that holds sake lees. The Fukuro-sage's urine has a powerful smell that can disorient humans and render insects and small animals unconscious.

Kasha [+]

Kasha, a messenger of hell, is a fiery monster known for causing typhoons at funerals. Anatomical features include powerful lungs for generating typhoon-force winds that can lift coffins and carry the deceased away, as well as a nose for sniffing out funerals, a tongue that can detect wind direction, and a pouch containing ice from hell. To create rain, the Kasha spits chunks of this ice through its curtain of perpetual fire.

Bisha-ga-tsuku [+]

The Bisha-ga-tsuku is a soul-stealing creature encountered on dark snowy nights in northern Japan. The monster -- which maintains a body temperature of -150 degrees Celsius -- is constantly hidden behind a fog of condensation, but its presence can be detected by the characteristic wet, slushy sound ("bisha-bisha") it makes. Anatomical features include feelers that inhale human souls and cold air, a sac for storing the sounds of beating human hearts, and a brain that emits a fear-inducing aura. The Bisha-ga-tsuku reproduces by combining the stolen human souls with the cold air it inhales.

Kijimunaa [+]

The Kijimunaa is a playful forest sprite inhabiting the tops of Okinawan banyan trees. Anatomical features include eye sockets equipped with ball bearings that enable the eyeballs to spin freely, strong teeth for devouring crabs and ripping out the eyeballs of fish (a favorite snack), a coat of fur made from tree fibers, and a nervous system adapted for carrying out pranks. The Kijimunaa's brain contains vivid memories of being captured by an octopus -- the only thing it fears and hates.
[Source: Shigeru Mizuki's Yōkai Daizukai, 2004]

40 Useful Sites To Learn New Skills

The web is a powerful resource that can easily help you learn new skills.  You just have to know where to look.  Sure, you can use Google, Yahoo, or Bing to search for sites where you can learn new skills, but I figured I’d save you some time.
Here are the top 40 sites I have personally used over the last few years when I want to learn something new.

1. Hack a Day - Hack a Day serves up fresh hacks (short tutorials) every day from around the web and one in-depth ‘How-To hack’ guide each week.
2. eHow - eHow is an online community dedicated to providing visitors the ability to research, share, and discuss solutions and tips for completing day-to-day tasks and projects.
3. Wired How-To Wiki - Collaborate with Wired editors and help them build their extensive library of projects, hacks, tricks and tips.  Browse through hundreds how-to articles and then add to them, or start a new one.
4. MAKE Magazine - Brings the do-it-yourself (DIY) mindset to all of the technology in your life.  MAKE is loaded with cool DIY projects that help you make the most of the technology you already own.
5. 50 Things Everyone Should Know How To Do - While not totally comprehensive, here is a list of 50 things everyone should know how to do.  It’s a great starting point to learn new skills.
6. wikiHow - A user based collaboration to build and share the world’s largest, highest quality how-to manual.
7. Lifehacker - An award-winning daily blog that features tips, shortcuts, and downloads that help you get things done smarter and more efficiently.
8. 100+ Google Tricks That Will Save You Time - Today, knowing how to use Google effectively is a vital skill.  This list links out to enough Google related resources to make you an elite Google hacker.
9. Instructables - Similar to MAKE, Instructables is a web-based documentation platform where passionate people share what they do and how they do it, and learn from and collaborate with others as the tackle new projects and learn new skills.
10. Merriam-Webster Online - In this digital age, your ability to communicate with written English is paramount skill.  And M-W.com is the perfect resource to improve your English now.
11. Lumosity - Learn to improve your memory by playing a series of fun and educational brain training games.
12. 100 Skills Every Man Should Know - Another compilation article with instructions to help you learn new skills.  This one says it’s geared for men, but I think most of these skills are applicable to women as well.
13. 5min Life Videopedia - Lot’s of great tutorials and DIY videos.
14. HowStuffWorks - Knowledge is power.  While this site isn’t exactly geared to help you learn new skills, it contains so much useful information that you’re bound to learn a skill or two while you browse.
15. StumbleUpon - A collective set of recommendations from thousands of hours of searching by web users who share your interests.  It’s basically a recommendation engine.  Users add to this engine by providing their personal recommendations on what sites are worth your time.  If you select topics and tags of interest like ‘Self-Improvement‘ and ‘DIY,’ you’ll be learning new skills in no time.
16. Work.com - An extensive directory of how-to guides for beginning entrepreneurs.
17. Howcast - Hosts professional how-to videos as well as how-to wiki tutorials.  Howcast combines user ideas with the expertise of professional studio video to deliver what is nothing short of amazing, informative content.
18. VideoJug - The video content on this site covers a variety of topics including informative ‘How To’ and ‘Ask The Expert’ films that guide you step-by-step through everything and anything in life.
19. MakeUseOf - A booming daily blog that features cool websites, computer tips, and downloads that make you more productive.  Lot’s of insightful tips and tricks to learn.
20. WonderHowTo - This site is focused on one clear organizing principle: aggregating and linking to truly great, free how-to videos from which you can learn new skills.
21. SuTree - Another useful aggregator of how-to videos from all around the web.
22. Zen Habits - The ultimate productivity and self-improvement blog.  Zen Habits is about finding simplicity in the daily chaos of our lives.  It’s about clearing the clutter so we can focus on what’s important, create something amazing, and find happiness.  Lot’s of learning material here.
23. Academic Earth - Online degrees and video courses from leading universities.
24. About.com Videos - Another solid collection of how-to video tutorials.
25. PCWorld How-To - Lot’s of useful tutorials and guides related to fixing and modifying computers and other electronic gadgets.
26. Spreeder - This site is focused on teaching you one new skill:  speed reading.  And it does a great job of doing so.
27. Woopid - Watch free technology training videos.  Get help and answer your computer and gadget questions with thousands of video tutorials for PCs, Macs, and various software applications.
28. DIY Network - A go-to destination for rip-up, knock-out home improvement projects.  The site offers expert answers the most sought-after questions regarding creative projects for DIY enthusiasts.
29. Scitable - A free science library and personal learning tool that currently concentrates on genetics, the study of evolution, variation, and the rich complexity of living organisms.  The site also expects to expand into other topics of learning and education.
30. All Recipes - A complete guide to recipes and cooking tips.  If you’d like to learn to be a better cook, this site is for you.
31. 43 Folders - This site is more about inspiring you to follow-through with your goals than it is about learning new skills.  But I think following-through with your goals is a skill.  Most people never quite get there.
32. Dumb Little Man - Another awesome productivity and self-improvement blog hosting lots of useful information.
33. iTunes U - Hundreds of universities — including Stanford, Yale and MIT — distribute lectures, slide shows, PDFs, films, exhibit tours and audio books through iTunes U.  The Science section alone contains content on topics including agriculture, astronomy, biology, chemistry, physics, ecology and geography.
34. American Sign Language Browser - Teach yourself sign language online.
35. BBC Languages - Teach yourself a new spoken language online.
36. Delicious Popular DIY - Lots of popular DIY articles bookmarked by users from all over the web.
37. Khan Academy - Over 1200 videos lessons covering everything from basic arithmetic and algebra to differential equations, physics, chemistry, biology and finance.  Lot’s of educational material to help you learn new skills.
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Diabetic Neuropathy

What is diabetic neuropathy?

Neuropathy means nerve disease or damage. Diabetic neuropathy is nerve damage caused by diabetes. People with diabetes often have high blood sugar levels. Over time, high blood sugar levels can damage nerves throughout your body.
There are three kinds of diabetic neuropathy.

1. Peripheral neuropathyis damage to peripheral nerves. These are the nerves that sense pain, touch, hot, and cold. They also affect movement and muscle strength. The nerves in the feet and lower legs are most often affected. This type of nerve damage can lead to serious foot problems. The damage usually gets worse slowly, over months or years.
2. Autonomic neuropathyis damage to autonomic nerves. These nerves control things like your heartbeat, blood pressure, sweating, digestion, urination, and sexual function.
3. Focal neuropathyaffects just one nerve, usually in the wrist, thigh, or foot. It may also affect the nerves of your back and chest and those that control your eye muscles. This type of nerve damage usually happens suddenly.

What causes diabetic neuropathy?

Over time, high blood sugar levels from diabetes can damage nerves throughout your body. The higher your blood sugar levels, the more likely you are to have nerve damage. So controlling your blood sugar throughout your life is very important.
The older you get, and the longer you have diabetes, the more likely you are to have nerve damage. People with diabetes who drink too much alcohol are also more likely to have nerve damage.
About half of all people with diabetes end up getting diabetic neuropathy.¹

What are the symptoms?

Your symptoms will depend on which nerves are injured. You may not be able to feel pain, especially in your feet. This can lead to serious infections, because sores or other problems may not get treated.
When other parts of your body are affected, symptoms may include:

• Problems with digestion, such as bloating, belching, constipation, nausea and vomiting, diarrhea, and belly pain.
• Problems with body temperature, such as heavy sweating at night or when you eat certain foods. Some people may have reduced sweating, especially in their feet and legs.
• Problems with urination, such as finding it hard to tell when your bladder is full or finding it hard to empty your bladder completely.
• Sexual problems, such as erection problems in men and vaginal dryness in women.
• Heart and blood vessel problems, leading to poor circulation or low blood pressure. This may cause dizziness, weakness, or fainting when you stand or sit up from a reclining position.
• Trouble sensing when your blood sugar is low.

How is diabetic neuropathy diagnosed?

Your doctor will check how well you feel light touch and temperature and will test your strength and your reflexes. Tests such as electromyogram and nerve conduction studies may be done to confirm the diagnosis. You may need other tests to see which type of neuropathy you have and to help guide your treatment.
Doctors can't test for all types of nerve damage. So it’s important to tell your doctor about any pain or weakness you feel. Also mention heavy sweating or dizziness and any changes in digestion, urination, and sexual function.

How is it treated?

Treatment involves keeping blood sugar levels near normal. This will not cure the nerve damage, but it can help keep the damage from getting worse.
The type of treatment depends on your symptoms:

• Pain may be treated with medicines.
• Digestive system problems or blood vessel problems may be treated with medicines.
• Blood pressure problems may be treated with medicines and by wearing support stockings (also called compression stockings).
• Sexual problems may be helped with medicines or devices to improve erections or with lubricating creams that help vaginal dryness.
• A splint or brace may be used for a pinched nerve.

It is common in diabetes to lose some feeling in your feet. You could have a sore or other foot problem without noticing it. Check your feet every day. An untreated problem on your foot can lead to a serious infection or even amputation.
Be clear with your doctor about what is helping you feel better and what is not. You and your doctor can work together to find the treatment that helps you the most.

Can diabetic neuropathy be prevented?

Keeping your blood sugar levels near normal may help prevent neuropathy from ever developing. The best way to do this is by getting to and staying at a healthy weight by exercising and eating healthy foods.
Frequently Asked Questions

Learning about diabetic neuropathy:	What is diabetic neuropathy? What causes it? Can I prevent it? What are the symptoms? How do diabetic foot problems develop? How can I prevent diabetic foot problems?
Being diagnosed:	How is diabetic neuropathy diagnosed? What tests will I need?
Getting treatment:	How is diabetic neuropathy treated?
Living with diabetic neuropathy:	What can I do at home to relieve symptoms? Do I need to be careful when I exercise? How can I best care for my feet?