Sleep Cycles

**DanB** · 11-30-2017 04:08 PM

Just a question I thought someone could answer. If you were to wake up during the night, mid sleep cycle, regardless of which stage you were in, if you were to go back to sleep almost instantaneously or even take a few minutes, would you re-enter the cycle where you awoke or would you start the cycle from the beginning.

I was just wondering because if you attempt a WILD LD technique for example which involves waking up during the night, would you have to go through each stage again and REM sleep is towards the end of a sleep cycle which is, in average, 90 minutes long. I've never performed a WILD, but sounds like no-one waits 90 minutes or close to that to perform the technique. So scientifically speaking, what happens?

**Darkmatters** · 11-30-2017 06:31 PM

You enter the same cycle. In fact I've read that even if you wake for a few hours your REM cycle continues - so for instance if you get up in the morning and then take a nap a couple hours later you're still on the same REM cycle. I don't mean the same phase is still going on - of course a REM phase doesn't last a few hours (though by morning it is almost continuous), but I mean you're still on the same schedule of on/off phases. The REM cycle begins when the sun goes down as I understand it - I don't know if artificial light screws with it or not. And it continues until a few hours after you wake up in the morning and get out of bed. So yes, you can wake in the middle of a REM phase (though generally speaking we wake at the end of them) and then re-enter still in the same phase.

**Kaan** · 11-30-2017 08:51 PM

This question is interesting, and needs answers with scientific sources.
back in the past I started to read studies about sleep interruptions and what I remember is that it's complicated and that the interruptions (REM sleep interruptions, or N-REM interruptions) tend to modify the sleep schedule even the following nights.
Sorry I didn't take notes of the sources link but you can search by yourself.
The subject is very interesting.

**TravisE** · 12-05-2017 01:39 AM

This is interesting, and it seems to be possibly not as simple as it would seem. In my informal experience, it even seems that the cycle can effectively “continue in the background”, so to speak, during brief awakenings. For instance, from the time I first fall asleep at the beginning of the night, I typically will wake up from my first REM cycle somewhere around 60 to 90 minutes later, but in cases where my sleep is somehow interrupted before this happens (or even if I come very close to falling asleep, but don't quite reach it in the first place for some reason), when I return to sleep I'll often hit REM much sooner than expected. In many of these cases, I find that the time I reach REM is about the same time it would have been had I been asleep the whole time rather than awake.

This is anecdotal, and I haven't really studied or investigated this behavior in anything that could be considered proper in a scientific sense, so perhaps I'm missing the boat here. I don't know for sure what happens during much longer awakenings (more than an hour or so).

However, in the context of performing a WILD, it's recommended to wake up briefly at some point in sleep where you've already gone through a few full sleep cycles. By this point, the NREM periods are shorter, and REM occurs much more often and for longer periods. So, you won't necessarily have to wait a full 90 minutes for REM to occur.

Even if you did go through an entire early-night sleep cycle with full-length NREM, though, and manage to retain lucidity (which is possible, but very difficult), the experience may well be far from dull, as a lot of very interesting things happen in the brain and mind during the various NREM sleep stages… though that's probably a different discussion.