Wednesday, December 5, 2007

When and how long to sleep

Talking with my coworker today we go on to the subject of sleep. The topic is one that has been perplexing me more and more recently due to a couple of factors. First, when I sleep to long I wake up with a rather sore back. This could be due to the bed that we purchased a few months back or maybe a lack of stretching and exercising daily or my bad posture as I'm writing this blog entry. Ok, that's better. Nevertheless, it got me to thinking that too much sleep may be too much of a good thing. Looking around the Internet seems to justify this assumption.
Taking those who had not made any change in their sleeping habits between 1985-8 and 1992-3 as their baseline (7 hours per night being the figure normally recommended as an appropriate period of sleep for an adult) they were able to see what difference having reduced the amount of sleep over time made to mortality rates by 2004.

Those who had cut their sleeping from 7hours to 5 hours or less faced a 1.7 fold increased risk in mortality from all causes, and twice the increased risk of death from a cardiovascular problem in particular.

Warwick - 2007.09.24
While another CNN Health article had this to say about sleeping for long periods of time
Eight hours of nightly sleep is not the health panacea you were brought up to believe, according to a study released Thursday suggesting a link between too much slumber and a shorter life span.

CNN Health - 2002.02.15
Of course these claims did not go without objection from none other than the National Sleep Foundation
The National Sleep Foundation, which recommends eight hours of sleep per night for optimal health, immediately attacked the study's findings and said they can do nothing but cause the public unnecessary confusion and concern.

CNN Health - 2002.02.15
My coworker says that he always aims for 6.5 to 7 hours per night as that fits the natural sleeping patterns of most adults, which, by the sounds of it, seems to be right on. I took a look at this as well and found out, or rather, refreshed myself on the cycles of sleep. The primary components are REM and NREM (I'm just going to be paraphrasing from wikipedia for a good remainder of this... so check out the sleep article instead for better explanations.) If I was to break up the cycle into a 6 hour night, this is probably what it would look like...

@ 90 min sleep cycles
1:00 to 1:22 REM
1:22 to 2:30 NREM
2:30 to 2:52 REM
2:52 to 4:00 NREM
4:00 to 4:22 REM
4:22 to 5:30 NREM
5:30 to 5:52 REM
5:52 to 7:00 NREM
7:00 to 7:22 REM
7:22 to 8:30 NREM

go to bed at 1:00 am -- optimal wake up time is around 7:20 am. Going to 7:30 will probably start to see you slipping back into NREM.

@120 min sleep cycles
1:00 to 1:30 REM
1:30 to 3:00 NREM
3:00 to 3:30 REM
3:30 to 5:00 NREM
5:00 to 5:30 REM
5:30 to 7:00 NREM
7:00 to 7:30 REM
7:30 to 9:00 NREM

I guess as long as you aren't slipping into deep NREM then your still safe from the groggy affects of a poorly timed sleep, but by just using the numbers from these two charts, 6.5 hours of sleep looks to be rather optimal.

And speaking sleep, it's about time I got some.


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