Why Do We Sleep? – Instant Egghead #55

Would it upset you to find out
you had a chronic brain condition that causes you to lose consciousness
for many hours at a time and periodically experience
paralysis and hallucinations? What I’ve described
are the symptoms of sleep. If you live to be 80, you will spend
around 26 years of your life in this state. Yet scientists still don’t agree on why. Some say we shouldn’t ask why we sleep, but why we are awake
when we don’t need to be, using precious energy
and possibly getting into trouble. The big brown bat is only awake
for around 4 hours just after the dusk. which maximizes its chances of eating and minimizes its chances of being eaten. But large herbivores have to spend
a lot of time foraging and have a few places to hide. So they can’t afford to sleep
for more than a few hours a day. If there is some universal
function of sleep, a goat somehow accomplishes it
in 5 hours, a tiger in 15 and a dolphin
with one eye open. Still there’s plenty of evidence that slumber is more
than just than laying low. The whole host of body functions
are enhanced during sleep.>From tissue repair, to immune function, to blood sugar control. But the most immediate consequence of sleep deprivation
is that we can’t think as well. Studies show that people who sleep before and after learning something new perform better on tests on memory and problem solving. This may indicate that sleeping brain reinforces
and archives new memories. But there’s also evidence that sleep weakens the connections between brain cells, in a way that it keeps important information, while reducing the clutter. But how exactly this happens
remains unknown. And it doesn’t explain why some animals
sleep much longer than others. Ultimately, some combination
of these ideas would probably explain why we spend a third of lives unconscious. For Scientific American’s Instant Egghead,
I’m Joss Fong.