Why Sleep?

Sleep is an ancient behavior shared among a vast number of species.

Deprived of sleep a creature’s life systems will soon degenerate leading to eventual death.

Thomas Edison was famous for saying that sleep is a waste of time. The truth, however, is that we cannot exist without it.

Yet the actual purpose of sleep remains a mystery.

Here is a brief overview of current theories:

* It allows the body to clear itself of neurotoxins created throughout the day

* It enables the consolidation of key memories

* It limits an organism’s active time lessening its exposure to environmental dangers (adaptive theory)

Some of these reasons would seem to apply across a broad range of creatures. Yet some seem applicable only to “higher” levels of organisms.

Take memory consolidation. I can certainly see my brain needing downtime to sort through the vast amounts of information it acquires throughout the day.

But what about our cat?

He sleeps 18 hours a day and I’d be hard-pressed to understand him needing that much time to consolidate his few hours-worth of memories (consisting primarily of eating chow, stalking through the grass, and pouncing on Legos.)

Maybe once the phenomenon of sleep was added to the genetic toolbox, as it were, it was employed for different uses in different species?

This is possible since the flavor and process of sleep varies widely between species. Our sleep, for example, is not like that of dolphins (who must stay partially awake in order to breathe). Nor is the dolphin’s sleep like the equivalent state in various insects known as torpor. And what about trees and plants, do they perhaps have a period of rest that we’ve not yet detected, beyond their winter repose?

Maybe the answer to the mystery of sleep is complicated because it serves a variety of purposes, each dependent on a species’ particular need and environment.

Then again maybe sleep is about something else entirely different than what we’ve supposed.

Maybe even way different.

In either case, it would be good to know the answer because we humans spend so much of our lives lying horizontally.

How much time do we spend sleeping?

The answer will either amaze or horrify you.

If you count the average daily sleep time at 8 hours, then the amount we sleep per year is 4 months.

Yup. We could essentially start our calendars on May 1st.

Carrying this forward, in the average human lifespan of 70 years the total amount of sleep works out to a whopping 23 years.

Two decades is an enormous time investment in one activity.

Clearly the process is critical.

But for what?

For what purpose must our eyes be closed, our senses dulled, and our bodies be held in partial paralysis?

The mind wanders…