I was talking this afternoon to a friend who was saying she was having trouble getting up in the morning recently because she was getting up two hours earlier to take her husband to work. While we were on the subject I remembered a study I'd read several years ago about the natural rhythms of sleep. I went and looked it up so I could tell her the straight account.
Studies show that the length of sleep is not what causes us to feel refreshed upon waking. the key factor is the number of complete sleep cycles we enjoy.
Each sleep cycle contains five distinct phases, which exhibit different brain-wave patterns. For our purposes, it suffices to say that one sleep cycle lasts an average of 90 minutes: 65 minutes of normal, or non-REM (rapid eye movement) sleep; 20 minutes of REM sleep (in which we dream); and a final 5 minutes of non-REM sleep. The REM sleep phases are shorter during earlier cycles (less than 20 minutes) and longer during the later ones (more than 20 minutes)
If we were to sleep completely naturally, with no alarm clocks or other sleep disturbances, we would wake up, on the average, after a multiple of 90 minutes--for example, after 4 1/2 hours, 6 hours, 7 1/2 hours, or 9 hours, but not after 7 or 8 hours which are not multiples of 90 minutes.
In the short period between cycles we are not actually sleeping; it is sort of twilight zone from which, if we are not disturbed (by light, cold, a full bladder) we move back into another 90 minute cycle.
A person who sleeps only four cycles (6 hours) will feel more rested than someone who has slept for 8 or 10 hours, but had not been allowed to complete the last cycle because of being awakened before it was completed....."
When I first read this I did a conscious trial of the theory and surprisingly, it worked. I would plan to be in bed at 10:30 if I needed to wake up at 6:00. This gave me a full five sleep cycles and I woke up naturally. For a while I did it consciously but then I guess it got to be a habit and I forgot about it.
Now that it all came back to mind I started reviewing my present sleep habit. And guess what! Even though I don't have to wake up at any special time and I can sleep when I want to, I'm naturally following that cycle pattern.
I've noted on here a lot of times that I'm frequently awake very early in the morning and I'm bright eyed and bushy tailed. Even though I go to bed a midnight I wake up at close to 4:30. That is only 4 1/5 hours but exactly 3 sleep cycles. And I'm awake.
Now I can put myself back to sleep at 4:30 if I try--get up and use the toilet wash my face with warm water, turn on the fan so it is chilly and I have to snuggle under a blanket to be warm--and I'll fall asleep for another 90 minutes. And when I wake up then I'm up for the day.
If you are getting up exhausted in the morning, try counting backward from your necessary wake-up time so that you will have a specific number of full sleep cycles. Plan your bed time 3, 4 1/2, 6, 71/2 or 9 hours earlier than your rising time. If you do that, I'll bet you wake up more rested...
Try it. it is kind of neat how it works.