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| | 90 Minutes Sleep Cycle - lifehack.org (Site not responding. Last check: 2007-10-20) |
 | | 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 period between cycles we are not actually sleeping: it is a sort of twilight zone from which, if we are not disturbed (by light, cold, a full bladder, noise), we move into another 90-minute cycle. |
 | | This article posted on Lifehack.org suggests that the overall number of hours one spends sleeping is not as important as the number of 90-minute cycles of sleep you get. |
| www.lifehack.org /articles/lifehack/90-minutes-sleep-cycle.html (1234 words) |
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