Real talk: I love sleeping, and I like to think I'm good at it too. When my head hits that pillow and it's time to catch some zzz's, I'm out.
But a lot of people really struggle with sleeping. George Clooney and Rihanna have been open about how it's hard for them to unwind and fall asleep at the end of the day. Jennifer Aniston said that when she wakes up in the middle of the night, she has a "committee in her head" that "won't shut up."
Every human and animal experiences sleep differently, and that's what makes it so mysterious.
"You have animals, for instance, like elephants, that sleep for as little as two hours a day, normally, and animals like bats that are reported to be sleeping up to 20 hours a day," explains sleep researcher Giorgio Gilestro.
Giorgio Gilestro is a professor in System Neurobiology at Imperial College London and he's been leading research in fruit flies to try to determine the biological function of sleep.
"The idea that scientists have been looking for one universal function of sleep makes this very difficult to reconcile because you will have to come up with a function that requires two hours in an elephant, but 20 hours in a bat. And this is not normally how we interpret biology."
Humans have been thinking about sleep and its difficulties since we first woke up. Gilestro recounts the epic of Gilgamesh, where he's challenged to stay awake for six days and seven nights in a test to become immortal.
"So people were able to recognize and describe sleep long before we had scientific instruments to measure it," says Gilestro.
"Generally, it is the realization that animals have to enter a state of apparent vulnerability. So you kind of almost lose consciousness. It's the fact that animals need to basically cut themselves out from the environment and enter a state that is completely different. That's our starting point."
This leads to the theory that a major function of sleep has to do with the brain eliminating waste, reenergizing cells, and classifying memories. For this to happen, our bodies cycle through rapid eye movement sleep (REM) and non-REM sleep.
We start with non-REM sleep, which has three main stages. The first step occurs right as our bodies transition into being asleep. We're barely sleeping here and can be easily woken up. This lasts for a max of 10 minutes.
Then we move to the second stage where we're lightly sleeping. Our body temperatures lower, and our breathing and heart rates are regulated. This section can last anywhere from about 25 minutes to an hour.
At this point, we move into the third and final step of non-REM sleep. This is our deep sleep that lasts for about 20 to 40 minutes. Our brains are pretty active here, and that's one of the reasons why it's so difficult to wake people up during this stage.
Up next is REM sleep. REM earned its name -- rapid eye movement -- for a reason. During this stage, our eyes and eyelids twitch like crazy because our brains are having their nightly fiestas. Our bodies become temporarily paralyzed and our breathing increases as our brains go wild with activity.
"When we sleep, we somehow lose consciousness to a certain extent. You know, we go into a different world," Gilestro says.
When we wake up from a good night's sleep, in theory, we will feel fully rested and invigorated with energy. But when we do not get enough sleep, like in instances of sleep deprivation, those biological processes are incomplete, which can negatively affect our cognitive abilities.
Because everybody sleeps and dreams differently, advice for getting better sleep will vary too -- you need to figure out a routine that works for your body.
Wind down before you go to bed. Playing a fast-paced video game or watching an emotional and stressful movie (or sports game) can be detrimental for sleep quality.
Remove all lights and noises from the bedroom. This means no night light, no television, no sound machines.
Finally, you want quality, not quantity. Fewer uninterrupted hours of sleep in an appropriate environment is actually better for you than more sleep in a bright, loud environment.
For more sleep hygiene recommendations, and a dreaming theory that could explain why some people believe they were abducted by aliens overnight, listen to the latest episode of Seeking A Scientist.
Additional sources from Seeking A Scientist:
Seeking A Scientist is a production of KCUR Studios. It's made possible with support from the Stowers Institute for Medical Research, where scientists work to accelerate our understanding of human health and disease.
It's hosted by Dr. Kate Biberdorf, AKA Kate the Chemist. This episode was mixed by Olivia Hewitt and Suzanne Hogan. Our senior producer is Suzanne Hogan. Our editor is Mackenzie Martin. Our digital editor is Gabe Rosenberg.