The National Sleep Foundation position statement is that adults should get between seven and nine hours of sleep per day. This is now being questioned by other scientists and expert groups.
Studies done by the Department of Psychiatry at the University of California, San Diego suggest that there is no statistical health-related reason to sleep longer than six-and-a-half hours daily.
When it comes to cancer, data from the Cancer Prevention Study II (CPSII) of the American Cancer Society, which included more than 1.1 million participants from 1982-1988, suggests that sleeping five hours per night is slightly safer than sleeping eight hours per night.
In a previous article, Just How Much Sleep Do YOU Really Need? I shared the National Sleep Foundation recommendation that adults, including those over age 65, require between seven to nine hours of sleep. I also stated that the ability to consolidate sleep explains how humans are able to function with less sleep compared to other primates.
In trying to answer the question: How you know if you (did) get enough sleep, one clue is whether you wake up at the same time every day without needing an alarm clock. This should pretty much hold true for the work week and the weekend. When the natural wake up time is the same on all seven days, it is a good indicator that your body is getting the right amount of sleep.
Inevitably, that efficiency of sleep suffers when “life” gets in the way and we allow the stresses of modern life to affect our schedule.
If we do accept that our body can figure out the right amount of sleep that each of us needs, then what would be the natural sleep-wake schedule for a person who is not influenced by all the demands or stimuli of the modern world? A group of scientists decided to look at just that.
A study published in the journal Current Biology looked at three groups of hunter gatherers in Namibia, Tanzania, and Bolivia. These were societies that did not have the trappings of modern life. Devices recorded the sleeping and waking times as well as light exposure of 90 adults for more than 1,000 days.
The data captured revealed that most of the individuals slept fewer than seven hours. So despite the fact that they slept close to the lower accepted safe level of recommended sleep, they were in good health, had lower levels of obesity and more optimal blood pressure control. Since clocks and electrical “waking” devices were not available, what drove their sleep and wake times?
It turns out that temperature is a key player in this equation of sleep. These natives stayed up until after sunset. There was no modern heat, so the room temperature dropped throughout the night and wake-up time coincided with the coldest moment in the morning. Their sleep-wake cycle was guided by temperature. This finding may give some insights on how to deal with insomnia, by using room temperature settings.
This study suggests what sleeping habits might be like if we were not influenced by work schedules, television, artificial light, and stimulation from tech-device screens and other modern entertainment. Most experts believe that sleep cycles are dramatically impacted by modern lifestyle, the long workdays, the lack of disconnecting from our tech devices, and late-night screen time.
The striking finding is that there was not much difference in the patterns of these three native groups in spite of their being geographically isolated from each other. The sleep findings are therefore assumed to be a reflection of natural sleep-wake patterns in humans if there were no outside influences.
The real focus of this discussion falls on quality of sleep rather than quantity of sleep. The phenomenon of consolidation of sleep has to fall in the right block of time; needs to be uninterrupted and cover all the appropriate stages of sleep, in order to achieve healthy and adequate balance of brain function. When this happens, restorative sleep, even of shorter duration, is sufficient.
What we really see from this study is that sleep needs for us are the same, regardless of geographic location or life circumstance. Still, there is likely a “perfect” amount of sleep for each of us. Using the technique of waking up without an alarm clock to identify the optimal duration of time, and then sticking with that schedule seven days a week will allow you to reap the health benefits from a commitment to optimal sleep patterns.
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Eli Hendel, M.D., is a board-certified internist/pulmonary specialist with board certification in Sleep Medicine. An Assistant Clinical Professor of Medicine at Keck-University of Southern California School of Medicine, and Qualified Medical Examiner for the State of California Department of Industrial Relations, his areas include asthma, COPD, sleep disorders, obstructive sleep apnea, and occupational lung diseases. Favorite hobby? Playing jazz music. Find him on Twitter @Lung_doctor.