Saturday, June 28, 2008

Sleep (PART 2)


To continue my research on what should be the optimal amount of sleep, I looked at scientific evidences. Scientific evidences are also one of the ways God speaks to us, by revealing what He knows, since He created everything.

I found that the optimal amount of sleep is not a meaningful concept unless the timing of that sleep is seen in relation to an individual's circadian rhythms. A person's major sleep episode is relatively inefficient and inadequate when it occurs at the "wrong" time of day. The timing is correct when the following two circadian markers occur after the middle of the sleep episode but before awakening:


1. Maximum concentration of the hormone melatonin,
2. Minimum core body temperature.



The National Sleep Foundation in the United States maintains that 8 to 9 hours of sleep for adult humans is optimal and that sufficient sleep benefits alertness, memory and problem solving, and overall health, as well as reducing the risk of accidents. A widely publicized 2003 study performed at the University of Pennsylvania School of Medicine demonstrated that cognitive performance declines with fewer than 8 hours of sleep.


However, a University of California, San Diego psychiatry study of more than one million adults found that people who live the longest self-report sleeping for 6 to 7 hours each night. Another study of sleep duration and mortality risk in women showed similar results. Other studies show that "sleeping more than 7 to 8 hours per day has been consistently associated with increased mortality", though this study suggests the cause is probably other factors such as depression and socio-economic status which would correlate statistically. It has been suggested that the correlation between lower sleep hours and reduced morbidity only occurs with those who wake after less sleep naturally, rather than those who use an alarm.

Causal links are currently speculative: the available data may only reflect comorbid depression, socioeconomic status, or even alcohol use, for example. These studies cannot be used to determine optimal sleep habits, only correlation — and empirically observed correlation is a necessary but not sufficient condition for causality. A need for 9 or 10 hours of sleep a day, or only 5 to 6, may or may not have the same cause as the shortened life span. In other words, long or short sleep duration itself has not been shown to be a cause of early death.

Researchers from the University of Warwick and University College London have found that lack of sleep can more than double the risk of death from cardiovascular disease, but that too much sleep can also double the risk of death. Professor Francesco Cappuccio said: “Short sleep has been shown to be a risk factor for weight gain, hypertension and Type 2 diabetes sometimes leading to mortality but in contrast to the short sleep-mortality association it appears that no potential mechanisms by which long sleep could be associated with increased mortality have yet been investigated. Some candidate causes for this include depression, low socioeconomic status and cancer-related fatigue. In terms of prevention, our findings indicate that consistently sleeping around 7 hours per night is optimal for health and a sustained reduction may predispose to ill-health.”



So what is the conclusion? Looks like the optimal amount of sleep is 7 to 8 hours. Of course, different people will have different requirements of sleep, so I guess some will only need 7 and some will need 8 to perform optimally the next day.


As for me, I will seriously start to adopt 7 hours of sleep, since that is the minimum amount, and also, I think it is absolutely biblical, since 7 is the perfect number of the Lord. I'm not surprised why 7 hours of sleep is strongly correlated with Psalm 127:2, eventhough it's not found in that verse. I want to perform optimally. And I want to live to 120 years. So it's time I get rid of my bad habit of NOT SLEEPING, of sleeping only 1/2/3/4/5/6 hours every night. I'm 29 years old and it's not too late to change. No doubt, my body could have been "damaged" by my 10 over years of sleep deprivation, but I believe it's better late than never. And God will help to restore the harm done. I hope you guys would do the same too, to take good care of yourself and your body.

Sweet dreams!


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