Caffeine is thought to block the receptor for adenosine, a critical chemical messenger involved in the homeostatic drive for sleep. If that were true, then caffeine would be most effective if it were administered in parallel with growing pressure from the sleep homeostatic system, and also with accumulating adenosine.

To test their hypothesis, the scientists studied 16 male subjects in private suites, free of time cues, for 29 days. Instead of keeping to a 24-hour day, researchers scheduled the subjects to live on a 42.85–hour day (28.57-hour wake episodes), simulating the duration of extended wakefulness commonly encountered by doctors, and military and emergency services personnel. The extended day was also designed to disrupt the subjects’ circadian system while maximizing the effects of the homeostatic push for sleep.

Following a randomized, double-blind protocol, subjects received either one caffeine pill, containing 0.3 mg per kilogram of body weight, roughly the equivalent of two ounces of coffee, or an identical-looking placebo. They took the pills upon waking and then once every hour. The goal of the steady dosing was to progressively build up caffeine levels in a way that would coincide with—and ultimately, counteract—the progressive push of the homeostatic system, which grows stronger the longer a subject stays awake.

The strategy worked. Subjects who took the low-dose caffeine performed better on cognitive tests. They also exhibited fewer accidental sleep onsets, or microsleeps. EEG tests showed that placebo subjects were unintentionally asleep 1.57 percent of the time during the scheduled wake episodes, compared with 0.32 percent for those receiving caffeine. Despite their enhanced wakefulness, the caffeine-taking subjects reported feeling sleepier than their placebo counterparts, suggesting that the wake-promoting effects of caffeine do not replace the restorative effects gained through sleep.

Coffee, tea, and other caffeine-containing beverages are tools. Don’t drink more than you need to and slow the rate of your drinking to spread it out. Keep in mind that once you reach the point where you don’t need to maintain a high feeling of wakefulness that you should immediately stop drinking it.

Link

Related Leave a Comment