Wednesday, October 28, 2015

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!

Wednesday, October 14, 2015

Sleep and heart disease

Certain sleep disorders such as obstructive sleep apnea have been linked with cardiovascular disease. This article reviews research about sleep duration and quality and coronary artery disease. I only have access to the article and the abstract. Researchers asked subjects to rate their sleep quality and the amount of sleep they get. The results showed that those who slept 5 or less hours, or 9 or more hours, had increased rates of coronary artery calcification and stiffness - both of which are early signs of coronary artery disease.

As far as I can tell, sleep quality and duration were assessed via questionnaire. There was no sleep study or other objective sleep duration measurement such as actigraphy. So it could be that some of the subjects had poor sleep quality from un-diagnosed obstructive sleep apnea, and that could account for some of the increased rates in coronary artery disease.