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Do afternoon naps help or disturb sleep later on at night?

There are two processes in the brain that create sleep drive in general. The first is the body’s natural “clock.” That clock dictates that we will become sleepy between 3 a.m. and 5 a.m., and also a little bit in the afternoon. It paradoxically creates wakefulness at around 8 p.m., during a time called ’the forbidden zone of sleep.’

A second process, called “Process S,” where the “S” stands for ’sleep,’ makes our bodies sleep more deeply if we stay awake for longer periods in between periods of sleep. We think that Process S is driven by the build-up of adenosine in the brain over time. Caffeine antagonizes, or interferes with, adenosine.

If you take a nap, the brain gets rid of adenosine rather quickly. Napping will indeed make you less likely to be able to go to sleep as successfully at bedtime. However, this isn’t the only thing driving you to sleep when you go to bed at night. Insomnia patients are asked not to nap because we want to keep as much of Process S going as we can. But we also have to think about the clock aspects of sleep. Both are involved in whether a person sleeps at a particular time.

March 8, 2012 at 10:00am

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