Why do naps last 1 – 2 hours, but we can sleep for 8 hours straight at night?

Question

I’ve just noticed, that when I take a nap, my body wakes myself up within 1 – 2 hours. This is probably true for everyone else too. But our bodies allow us to sleep for 8 hours at night. Why can’t our bodies nap for a full 8 hours without waking up? How does our body know this? How does our body differentiate between napping vs a nights sleep?

In: Biology

Answer 1

Sometimes you can’t. I’ve had trouble sleeping for more than two hours at a time for many many years. An old friend of mine got like that too. I just take one or two two-hour naps a day. Plus due to a very long and involved story of being fucked over by the donation of a shitty bed by a very passive-aggressive friend of the family, my sister sprang one day for the best mattress in the store. She went into serious debt to pay for it. A queen-size Sealy Posturepedic pillow-top mattress. Meaning the entire top of the mattress is a pillow. I usually fall asleep within a minute’s time. Yesterday’s two hours’ sleep was a total power nap. I knew I wanted to keep working at the computer, but my eyes were crossing. So I just walked over in my clothes, laid down, knowing that a “minute” later it would be two hours, and then it was. Just like that. I sprang right back up and sat down again. Went back to what I was doing. After at least five years of every day being like this, my brain has adapted. I get heavy REM sleep during those couple of hours. According to an old psychiatrist, it can happen if you have long-term insomnia.

To actually answer your question and not just talk on a tangent, it’s actually very difficult to break out of the circadian cycle. People who work third shift have to learn to do it. When around people who aren’t night owls, you then remember that there are actually people who get sleepy at two a.m. Your body just wants to go into long-term downtime. You can offload the RAM and clear out your head with a nap, but usually you need to go through the long process of being asleep and not dreaming before the dreams start to kick in and you get the good REM.