Sleep patterns of traditional societies

Here is an interesting article about a research study that received lots of media attention. The researchers studied the sleeping patterns of three traditional societies in Africa and South America - apparently their lifestyles resemble ancient hunter-gatherers. Results showed that the three groups slept 6 hours and 25 minutes per night on average. The sleep duration was similar between the three groups. Despite getting only 6'25" of sleep per night, the participants did not complain of feeling sleepy in the daytime and very rarely took naps.

A surprising result was that natural light did not affect the timing of sleep, as all three groups fell asleep on average 3.3 hours after sunset - which is the time when the temperature was falling. Even more interesting was that all of the group members woke up when the temperature was at its lowest.

Of note, insomnia was extremely rare - two of the groups did not even have a word for it!

Older Americans sleep as well as younger Americans

In my training, I was taught that older adults, in general, go to bed early, get up early, and have poorer sleep overall than younger adults. This article discusses new research about the sleep habits of older Americans. Researchers did telephone surveys and found that many of the respondents had sleep schedules and sleep quality similar to those of younger adults.

These results are not actually surprised, as recent studies have shown similar results and Dr. Ancoli-Israel has lectured about this recently. It is true that some sleep disorders are more prevalent as we age, but getting older does not automatically mean you are destined for poor sleep.

Sleep Timing, Weight Status, and Activity Patterns in Children

Studies have indicated a relationship between short sleep duration and obesity in children and adults. The cause of the elevated weight in short sleepers is not known. There is relatively little research done on the relationship between the timing of sleep, weight, and activity patterns. In the Journal Sleep is a study about this topic. The researchers classified sleep timing as early to bed / early to rise, early to bed / late to rise, late to bed / early to rise, and late to bed / late to rise. They studied Australian children ages 9 - 16 years old, and surveyed their sleep habits, physical activity, and measured their weight, height, and waist circumference.

The results showed children who were late to bed / late to rise were 1.5 times more likely to be obese, 1.8 times to have too little physical activity, and 2.9 times more likely to have excessive use of computers and television (a.k.a. screen time) than the early to bed / early to rise group. Interestingly, the greatest differences in the above measurements were between the late to bed / late to rise and early to bed / early to rise groups, which slept the same amount per night. There was little difference in early to bed / late to rise and late to bed / early to rise, which had an average total sleep time difference of over 2 hours per night. This is contrary to the prior studies that suggest sleep duration is linked to obesity. The results from this study imply that it is the timing of the sleep, not the sleep duration, that is associated with obesity.

Some advocate that adolescents be allowed to stay up late and sleep in, including later school start times. However, this might make the obesity problem even worse, according to the study results. If anything, this study suggests that children should be put to bed earlier and gotten up earlier.