I’m currently looking out my home office window as the sun rises on a cold, crisp, sunny December morning. There is a good foot or more of snow on the ground, and the sky is unusually bright for this time of year in the Metro Vancouver area. This brings to mind an interesting talk I recently attended, given by an expert in sleep research: Dr. Jerome Siegel, from the University of California at Los Angeles. This professor has conducted some fascinating research on the sleep patterns of hunter gatherer societies.
There were a few interesting take-home points from his talk. First, hunter gatherers, on average, sleep slightly less than people living in more modern societies. This seems to go against the common myth that we modern folk are all horribly sleep deprived, and that if we could only return to a more primitive lifestyle, we would sleep a lot more. Second, the sleep of hunter gatherers is not 100% tied to the presence or absence of daylight. One would think that, with no artificial light and increased potential for danger in the dark, such individuals would generally hunker down and go to sleep around sunset. On the contrary, they seem to go to sleep an average of a few hours after sunset. Third, there seems to be little or no insomnia, obesity, or cardiovascular disease. In the research reviewed by Dr. Siegel, this difference in health profiles between hunter gatherers and people in modern societies did not seem to be related to differences in activity level or calories burned throughout the day through physical activity. Fourth, some of the findings seemed to suggest that sleep is strongly related to circadian fluctuations in ambient and body temperature. Sleep generally occurred during a period of falling outside, ambient temperature, corresponding to a period of falling core body temperature. Therefore, how cool your room is at night may not be as important as whether the temperature is falling.
Finally, another interesting finding that relates more to the title of this blog was that hunter gatherers seem to get the most sunlight exposure in the relatively early morning. This seems to be because, near the equator, it is so hot during midday that people concentrate their activities in the morning and generally seek shade in the early to mid afternoon. We don’t know for a fact whether these individuals have better sleep than we do, but the absence of insomnia and the low prevalence of napping seem to suggest that hunter gatherers have slightly shorter but perhaps more compact, quality sleep. This could be due to many factors, but perhaps morning daylight exposure is among one of the important ingredients of a good night’s sleep. I’m aware of some evidence, although it is not based on the strongest research, that morning daylight exposure may enhance sleep. There has been some other research suggesting that exposure to light in the morning may be particularly important in alleviating depression. The proponents of light therapy, for example, often suggest that light machines be used for approximately 90 minutes, primarily in the morning. I have also noticed, anecdotally, that my mood, energy level, and sleep all tend to be better on days when I have had significant activity outside in the morning. Yesterday, I went for a lovely morning hike in the snow, and it seemed to give me an extra lift that persisted throughout the day. Further, I had a great sleep and woke up before my alarm went off this morning. This could certainly be a coincidence or related to other factors, but I’m definitely getting on board with the idea that being outside, actively exposed to daylight in the morning, is probably a good idea. For those of you who live in the Metro Vancouver area, take advantage of what little sunlight we seem to get in the winter. It is looking sunny for most of the week. Get out, get active, enjoy it while you can, and sleep well! ~ Alexander L. Chapman, Ph.D., R.Psych.