Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, I'm
Speaker 1: Christian Seger, and this is brain Stuff. Here's a quote
Speaker 1: for you from American lightbulb man Thomas Edison. He said
Speaker 1: sleep is a criminal waste of time, inherited from our
Speaker 1: cave days. Well, like Edison, we hear at brain Stuff
Speaker 1: hate sleep. That's why we wanted to do this episode
Speaker 1: to figure out why we have to do it. Normal
Speaker 1: people spend thirty of their lives asleep, and most are
Speaker 1: either like us and wish that they didn't have to
Speaker 1: sleep so they could get more done, or they just
Speaker 1: want to get a RESTful, uninterrupted night without waking up.
Speaker 1: Studies actually show that six adults claim to have problems
Speaker 1: sleeping at least a few nights a week. And here's
Speaker 1: the thing. Everyone's got to sleep. Yet we still don't
Speaker 1: know exactly why, but we're gonna try to do our
Speaker 1: best to crack that case today. That's right, let's review
Speaker 1: some theory reason for why we sleep, What happens when
Speaker 1: we sleep, and what happens when we don't. Even though
Speaker 1: we don't know why we sleep, there's all kinds of
Speaker 1: educated speculation. The most prevalent is that sleep gives our
Speaker 1: brain a chance to organize and process information, possibly through dreams. Basically,
Speaker 1: our brain takes all the sensory stimuli we received while
Speaker 1: we're awake and decides what to keep and where to
Speaker 1: file it. Everything else gets trashed. It's even possible that
Speaker 1: our ability to learn tasks actually benefits from quote sleeping
Speaker 1: on it as a process is better understood after our
Speaker 1: brain reviews and catalogs it. While most agree with this
Speaker 1: memory consolidation theory, it's tough to pin down since we
Speaker 1: all sleep so differently. And here's another theory. Sleep gives
Speaker 1: our bodies time to rest and repair. Or how about
Speaker 1: sleep lowers our energy consumption so we conserve the meals
Speaker 1: we eat. Other theories delve into the biochemical mechanism of
Speaker 1: the brain. In a series of experiments on mice, showed
Speaker 1: that cerebral spinal fluid was pumped around their brains while
Speaker 1: they slept, expelling waste like molecular detritus and toxic proteins
Speaker 1: into their livers for breaking down. So do we sleep
Speaker 1: just to flush the toilet on our cerebral commodes? Well,
Speaker 1: Other sleep researchers were skeptical of the study that I
Speaker 1: just mentioned pointing out that there are some big differences
Speaker 1: between a mouse's brain and humans. So while the answer
Speaker 1: to why we sleep isn't written in stone, we all
Speaker 1: know that when we sleep, both our mind and our
Speaker 1: body feel refreshed. We at least know what's happening when
Speaker 1: we sleep right well, most of us need between seven
Speaker 1: to nine hours of sleep at night, but that changes
Speaker 1: during different periods of life. For example, a newborn baby
Speaker 1: might sleep twenty hours a day, but by the time
Speaker 1: they're three months old, they recognize the circadian rhythm of
Speaker 1: sleeping at night and waking up in the morning. And
Speaker 1: when you're older, like senior citizen, older can probably get
Speaker 1: by on only six or seven hours a night. Regardless
Speaker 1: of how long you're a sleep, you must experience both
Speaker 1: R e M and non r e M stages to
Speaker 1: sleep well. That's rapid eye movement, not the band R
Speaker 1: E M from Athens, Georgia. A normal person spends of
Speaker 1: their sleep in R e M, with each session lasting
Speaker 1: between five and thirty minutes, and during this time our
Speaker 1: brain speeds up, our eyes and face might twitch in
Speaker 1: R e M because we're dreaming. We need around ninety
Speaker 1: minutes to fulfill a complete cycle of R E M
Speaker 1: N non R E M sleep, and researchers think this
Speaker 1: cycle ties sleep back to our ability to process tasks
Speaker 1: and memories. Recordings show that many of the same neurons
Speaker 1: that fire when we're learning are reactivated during R E M,
Speaker 1: consolidating the patterns into permanently wired connections. But don't sleep
Speaker 1: too much more than eight hours can lead to depression
Speaker 1: or even Parkinson's and heart disease. Of course, if we
Speaker 1: don't sleep, that's a whole other mess of problems. Rats
Speaker 1: will actually drop dead if they go more than three
Speaker 1: weeks without sleep. Us humans we get lethargic, cranky, and
Speaker 1: foggy headed at first, almost like we're intoxicated. We might
Speaker 1: even nod off into micro sleep for a few seconds,
Speaker 1: and this is what happens after one or two nights
Speaker 1: without sleep. By day three, we start hallucinating and lose
Speaker 1: the ability to recognize reality. That's if you're really pushing
Speaker 1: the boundaries of sleep. Simply failing to get enough sleep
Speaker 1: is connected to obesity, high blood pressure, a weakened immune system,
Speaker 1: heart disease, cancer, and diabetes. And it's no big revelation
Speaker 1: that lots of us don't get enough sleep. We might
Speaker 1: try to get by on caffeine or nicotine, and alcohol
Speaker 1: is a good sedative, but it doesn't actually provide the
Speaker 1: sleep we need for neural processing. So, in the words
Speaker 1: of the immortal poet Chris Ludicrous Bridges is, if you're tired,
Speaker 1: be quiet and go to sleep. Check out the brainstuff
Speaker 1: channel on YouTube, and for more on this and thousands
Speaker 1: of other topics, visit how stuff works dot com.