the “quarter life” of caffeine is usually about 12 hours, meaning that 25% of the caffeine in a cup of coffee consumed at noon is still circulating in your brain when you go to bed at midnight. That could well be enough to completely wreck your deep sleep.
Sleep quality is just as important as sleep quantity.”
But here’s what’s uniquely insidious about caffeine: the drug is not only a leading cause of our sleep deprivation; it is also the principal tool we rely on to remedy the problem. Most of the caffeine consumed today is being used to compensate for the lousy sleep that caffeine causes – which means that caffeine is helping to hide from our awareness the very problem that caffeine creates.