Why do we spend a third of our lives asleep?

G’day! Sleep in today? Bet you wished you could, huh? A fresh cup of coffee and a virtual treat will wake you up soon enough. Boy, people love their sleep, don’t they. I know I do. Can’t wait to snuggle down at night. By the same token, I can’t wait to get up in the morning. Nong will tell you. Anytime after 6:00 AM and the day’s half wasted! Awake! Refreshed! Recharged!  So why do we love our sleep so much that we spend about one-third of our lives asleep. If we live to be 75, why that’s pretty near…wait a second…two carry the seven…25 years. 

Scientists don’t really know why people sleep. They do know that we must sleep and, in fact, people can survive longer without food than without sleep. And people are not alone in this need – all mammals, reptiles and birds sleep.

Scientists theorize about why we sleep:

• Sleep may be a way of recharging the brain. The brain has a chance to shut down and repair neurons and to exercise important neuronal connections that might otherwise deteriorate due to lack of activity.
• Sleep gives the brain an opportunity to reorganize data to help find a solution to problem, process newly learned information and organize and archive memories.
• Sleep lowers a person’s metabolic rate and energy consumption.
• The cardiovascular system also gets a break during sleep. Researchers have found that people with normal or high blood pressure experience a 20 to 30% reduction in blood pressure and 10 to 20% reduction in heart rate.
• During sleep, the body has a chance to replace chemicals and repair muscles, other tissues and aging or dead cells.
• In children and young adults, growth hormones are released during deep sleep.
• When a person falls asleep and wakes up is largely determined by his or her circadian rhythm, a day-night cycle of about 24 hours. Circadian rhythms greatly influence the timing, amount and quality of sleep.

For many small mammals such as rodents, sleep has other particular benefits, as it provides the only real opportunity for physical rest, and confines the animal to the thermal insulation of a nest. In these respects sleep conserves much energy in such mammals, particularly as sleep can also develop into a torpor, whereby metabolic rate drops significantly for a few hours during the sleep period. On the other hand, humans can usually rest and relax quite adequately during wakefulness, and there is only a modest further energy saving to be gained by sleeping. When we don’t fall into a deep sleep, the fall in our metabolic rate is only about 5-10%.

Aaaaahhhh! Pardon the yawn. Better go have a nap, eh!

See ya!

Bob