Sunday, March 25, 2007

Bi-Phasic Sleep

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For the past year, I've noticed that my daughter sleeps 9 hrs at night, and about 1.5 - 2hrs nap in the afternoon. My daughter has been quite a model example of a biphasic sleeper. The biphasic sleeping schedule, in which you divide your sleep into two segments per day, is designed to maximize (well, increase) your effective sleep. The first segment is the nap, which is supposed to be 90 minutes in duration. The second segment is the core sleep, which is either 3hrs or 4.5 hrs in duration. The biggest advantage of biphasic sleeping is that you become just as productive but with less than the conventional 8hr sleep that most other humans require. There are many theories about the human sleep cycle. For instance, one theory states that humans sleep in multiples of 90 minute cycles. So, when you sleep for 8hrs, you wake up feeling groggy, but when you sleep for 7.5hrs, or 9hrs, you wake up feeling rested and energized. Steve Pavlina optimized his polyphasic sleeping to just over 20minutes in 4 hour intervals. Well, guess what: 90 minutes is an exact multiple of 22.5 minutes! No two humans are ever the same, so my own theory is that it's not a precise 90 minute sleep cycle for everyone; for some, it may be 95 minutes, for others it may be 85 minutes. Since my daughter sleeps in multiples of approx. 90minute cycles, would it not make sense that I should also be sleeping in 90 minute cycles, given that we share the same genetic DNA ?

Ever since I was laid off from work, I have been taking naps to supplement my core sleep at nights. My napping has not been consistent to say the least. Sometimes, I would take two 10min. naps, the first during 930a (PST) and 1130a (PST). At other times, I would take about a 1hr nap at around 130p, or a 20min. nap at around 1030a, or 5p.
So, since I am napping anyways at least once a day, I may as well try to structure it to conform to the biphasic sleep schedule to make it more efficient. The other reason for me to try this biphasic sleeping is because it fits my trading schedule. Since I live on the west coast, I must wake up by 630am at the latest, otherwise I will miss the market open for the day. The Wikipedia entry for BiPhasic sleep suggests that the 1.5 hr nap should be done at around 830pm. In my opinion, napping at 830pm would make it harder to transition to the biphasic sleep schedule. After all, if I sleep @830pm, why would I feel sleepy at the 130am core sleep?
I think I will try 12am to 430am as my core sleep, and take the 90minute nap at 130pm (which by the way, is 9hrs after 430am).
I will try this out for now and report on my biphasic sleeping progress as time permits.


Sam said...


Napping is generally healthy if it provides needed rest, is kept short, and dose not interfere with nighttime sleeping. However, napping should be avoided if makes a person less able to fall asleep at night.

Older people tend to nap more than younger people do because thay are less physically active and less stimulated. Napping may also help older people compensate for the changes in sleep that comes with aging and for interruptions in nighttime sleep caused by sleep disorders.

An additional reason older people nap relates to changes in blood supply to the brain. In younger people, blood vessels widen and narrow, keeping blood pressure in the brain constant even when blood pressure in the rest of the body is changing. In older people, blood vessels are less able to compensate for changes in blood pressure in the body. When blood pressure in the body decrease, as occurs after eating, blood pressure in the brain is more likely to decrease as well, possibly leading to sleepiness. The decrease in blood pressure in the brain is one reason older people may fall asleep after eating a big meal, even in a room filled with noise and commotion.

Read on Dr.Samantha Hement Insomnia Blog (

Phileo said...

Hi Sam,

Thanks for dropping by!
One of the articles in the website that you linked says "If you can reduce you sleep time and still function fully, so much the better."

In any case, I do not have insomnia, but thanks for providing the link....