Sunday 12 June 2011

Sleep and diversity

In an interesting article on sleep in traditional societies on Science News (which is not the news section of Science), Bruce Bower states that people used to sleep in groups and that differences in sleeping time where an advantage as it provided better protection for the sleeping group.
... sleep typically unfolds in shared spaces that feature constant background noise emanating from other sleepers, various domestic animals, fires maintained for warmth and protection from predators, and other people's nearby nighttime activities.
In traditional settings, however, highly variable sleep schedules among individuals and age groups prove invaluable, since they allow for someone to be awake or easily roused at all times should danger arise, Worthman holds.
Thus a diversity of sleep schedules may be well adaptive, may have been selected for by evolution as it provides better protection. It would be great if modern society would allow people to follow these natural needs, instead of forcing a fixed schedule on early birds and night owls.

By the way, the circadian sleep-wake cycle itself is an example of variability in the activity level. Science still wonders why we sleep. It may well be related to this variability, which allows one to be more active during the day; while at night the reserves are filled again and repairs are performed. A remaining question would still be why you need to close your eyes for this, which is dangerous.

Sleeping without mattress

I found the article linked on the page The Ergonomics of Sleep: Why a Hard Surface can Provide Sweet Dreams. This page argues that sleeping on a mattress is a recent invention and may not be ideal for everyone. To me it makes sense to use traditional behavior as Null-hypothesis; modern ideas are often useful (for instance, hygiene and vaccinations), but should be tested. Thus one week ago, I removed my mattress to see it this works for me and slept on the wooden panel below, but I did add an exercise mat and a comforter (German: Bettdecke) as cushioning. It is definitely not comfortable, but I sleep well, wake up much more alert and it is easy to get out of bed.

What makes it uncomfortable is that your weight is mainly born by your bones. If you sleep on your back your weight is on your heels, pelvis, shoulder blades and skull, on your side it is on your ankle, pelvis and shoulder, on your front the tops of the feet, the knees, pelvis, ribs (man) and collar bones. May there be a reason why exactly these places have no padding, no fat nor muscle? The reduced pressure on the weak body parts could maybe be beneficial for the circulation. Lying in a dimple on a mattress could change your posture (round back) and consequently your breathing.

I am curious what other people experienced and know about this topic; please leave a comment.

Further reading

More posts on paleo (diet and lifestyle topics inspired by evolutionary thinking).

Paleo and fruitarian lifestyles have a lot in common
A comparison of the main ideas and recommendations of these two lifestyles.
Natural cures for asthma?
Some ideas for natural ways, which helped me cure or reduce asthma.
Is obesity bias evolutionary?
A critical comment on an article, which states that humans have an intrinsic propensity to eat too much.
Freedom to learn
Forcing children to learn stifles their innate motivation to teach themselves and may thus be counter productive.
The paleo culture
After the Ancestral Health Symposium 2012, as discussion started about the sometimes self-centred culture of the paleo community