Can I catch up on what I miss?

摘要

Despite our best intentions, we don't always get enough sleep. So what happens when we party until dawn or shave of f a couple of hours each night? The need to sleep is controlled by a two-tier system. The circadian clock relies on light to keep your sleep/wake pattern within around 24 hours. Then there's sleep drive or sleep pressure. The longer you are awake, the more a chemical called adenosine builds up in your brain, sending signals that increase your desire for sleep (see diagram, right). "After 16 hours it should be at a screaming level that means you have to fall asleep," says Matthew Walker, who researches sleep at the University of California, Berkeley. "When you do, the pressure valve is released."