Using your circadian rhythm, part 2

On average, americans spend 8.7 hours a day sleeping - more than 28 years of their life! What the heck are we doing with that time? It seems excessive; on the other hand, it is clearly not optional. As far as keeping us alive, sleep is right up there with water, we can only go without for a few days before we risk death. For a long time sleep was thought to be passive, but now it is now known that we pass through 5 stages of sleep. They are called, somewhat unimaginatively, stage 1, 2, 3, 4 and REM (Rapid Eye Movement). Through out the night we pass through the successive stages from 1 to 4 and then back to 1 and then into REM. Then we start over with stage 1. These cycles take about 90 minutes.

A typical, 8 hour, nightly cycle

You may want to notice from the chart a few things. The first thing to notice is that REM sleep and Stage 4 (Deep sleep) are emphasized by color. This is because we think we are starting to understand what these stages do, and that they are important. The second thing to notice is that Stage 4 is more prevalent at the beginning of the night and REM sleep becomes more common latter in the night. The third thing to notice is that we spend a lot of time in Stage 2. As far as I know, no-one has any strong theories about what Stage 2 is for, but I think that eventually someone will discover that it is key to our mental health in some way.

Here is where the circadian rhythm comes in. It turns out that the stages of sleep that we go through are linked to our circadian rhythm - NOT to the length of the sleep. That is to say we do not start the same cycle every time that we go to sleep, but our cycle is determined by WHEN we start our sleep. So by napping in the early part of the night, we get a lot of Stage 4 sleep. A morning nap gives a lot of REM sleep, and a nap in the afternoon consists mostly of Stage 2 sleep.

Correlation between

monophasic sleep cycles and

circadian triphasic

It is interesting to note that the triphasic sleep pattern are similar, but more efficient than the monophasic pattern. There is less time moving through intermediate phases in the triphasic, and no intermediate short waking cycles. The triphasic data is a composite from Zeo sleep data. At some point, I would like to be able to start measuring data directly from my sleep cycle.

So on the triphasic sleep pattern, one gets about equal amounts of REM, Stage 2, and Stage 4 sleep. I think this explains why the triphasic schedule is so easy to change to, and has very little "adaptation" time.