Mind – Sleep May Be Nature’s Time Management Tool – NYTimes.com

Why do we sleep? From an evolutionary perspective there are two kinds of traits. The first is adaptive, traits that give a species abilities and behaviors that help individuals survive in order to pass along their genes. The second set of traits are side effects of the first. You get into a lot of interesting but fuzzy speculation here. For instance, did humans develop a belief in the supernatural because we dream? If so, it may be that those beliefs are a side effect of an adaptive behavior – sleeping, and dreaming – rather than adaptive in and of themselves.

The NYT gets in on the speculation in order to make use of the current buzz phrase “time management” and overachieving cult of getting-things-done (GTD). It’s kind of interesting anyway:

The answer may boil down to time management, according to a new paper in the August issue of the journal Nature Reviews Neuroscience. In the paper, Jerome Siegel, a professor of psychiatry at the University of California, Los Angeles, argues that sleep evolved to optimize animals’ use of time, keeping them safe and hidden when the hunting, fishing or scavenging was scarce and perhaps risky. In that view, differences in sleep quality, up to and including periods of insomnia, need not be seen as problems but as adaptations to the demands of the environment.

It seems obvious to me that conservation of energy during unproductive periods is the purpose of sleep. In my understanding, energy conservation is integral to evolution. Mutations have to engender really important new traits if they also result in increased energy usage. For instance, your brain requires an huge amount of energy. Because of this increased energy consumption, you need to find a lot more resources than you would otherwise. But it gives us humans a big enough advantage that the extra energy requirements make it worthwhile. It’s a trade-off. More energy requirements – think about the energy birds need to be able to fly – versus the ability to escape predators or devise solutions to feed yourself.

To be tongue-in-cheek about it – I went to bed after midnight and was awake at 5:30. That’s not a lot of sleep. But it can be explained by my need to code like a madman today to complete a task that will help me catch up on my bills. Doesn’t explain why I’ve spent the past 20 minutes writing this post. ;-)