It’s no secret that caffeine, the second largest US import (only surpassed by oil) is also America’s most widely-consumed pharmacological agent. But the drug that up to 90 percent of Americans consume regularly for the sake of productivity is not without its caveats. In this edition of The Neuroscience of…, we investigate the ways we help (and hurt) ourselves while studying for finals, and suggest a few ways to lend a hand to your academic marathon.
From the perspective of the brain, the trick to being prepared for any task requiring hours of sustained concentration is stamina. However, our brains are only programmed to attend to certain stimuli for limited amounts of time. What would happen if we spent hours fixated on a train’s whistle, without paying adequate attention to other relevant information (such as the train itself)?
When we absorb information, we make minute changes to the neural infrastructure of our brain through a process called plasticity. What we know isn’t merely the sum of our neurons – it is their interconnectedness. Therefore, when we learn, our brains shear off old, useless connections, and build up newer, more important ones. It is for this reason that studying important information is so much easier than banalities. For new information, the more connections we make with what we already know, the stronger it can be reinforced.
It is also for this reason that sleep is so important. Although little is known about sleep (but theories abound), we do know that it is critical to learning. Contrary to popular belief, the brain is actually quite active during sleep. Although we’re not certain of exactly what it is up to, we do know that it rapidly engages virtually all its parts, especially those that mediate newly-learned skills. For example, trying to finger a passage on the piano is difficult on the first day, but that night the brain tirelessly engages its motor circuits in what may be its attempt to make sense of it. As a result, practice the next day improves significantly. Without this process, learning simply does not occur. In several studies (which you have probably replicated on yourself), sleep-deprived individuals suffer significant deficits in learning and cognition, especially in test-taking environments.
So what’s the solution? Put down that book, whatever it is, and go to sleep. But that is generally a lot easier said than done. Approximately one-third of Americans get less than the recommended nightly dose, and only 11 percent of college students report getting the sleep they need.
Much of this can be chalked up to careless use of caffeine and alcohol. Many people drink alcohol before bed as a means of calming them, but it has actually been shown to increase the time it takes for REM sleep – the kind really critical to learning – to occur. The same is true of caffeine.
This is a problem easily solved by a little methylxanthine pharmacokinetics, a mouthful of a phrase that really means “how your body metabolizes caffeine,” but sounds much more impressive at a cocktail party.
A single dose of caffeine (approximately 100mg, the amount in a cup of coffee) is completely absorbed into the blood within 30-60 minutes. In four hours, it reaches its maximum blood concentration. Unfortunately, the half-life of caffeine is about five hours, meaning that an 8 a.m. 100mg cup of coffee will be with you for approximately 10 hours. It’s this aspect of the drug that interrupts sleep the most. An evening cup of coffee can stay with you all night, disrupting key sleep patterns the brain needs to integrate new information.
This can lead to caffeine “addiction.” Although not mediated by classical forms of addiction in the brain, reliance on caffeine is generally brought about by sleep deprivation. Overuse of caffeine makes sleep less effective, a symptom many groggy coffee drinkers treat with more caffeine.
The bad news is that this can lead to caffeine tolerance, in which larger doses are required to achieve the same effect. The good news is that unlike other forms of addiction, caffeine tolerance can be largely broken by a 5-7 day cold-turkey marathon. The other good news is that caffeine overuse is far from fatal – the lethal dose has been estimated at approximately 10 grams, the equivalent of 50-200 cups of coffee.
So what does all this mean for you, the overworked student in the throws of the last final exams of the year? Integrate your studies with what you know. Sleep enough. Don’t drink too late. Simple advice for an organ that’s anything but.