When I was in college, I informed my parents that they could stop hoping I would achieve anything close to greatness: I simply needed too much sleep. While President Barack Obama was up late sending emails and writing letters into the wee hours, and all my friends were telling me they could “sleep when they’re dead,” I was snoozing away critical hours.

Compared with giraffes, which zonk out for just 30 minutes a day, or dolphins, which rest only one-half of their brains at a time, I—who will gleefully luxuriate in nine hours of shut-eye now and then—am basically a lump who occasionally has wakeful moments.

Turns out I still might have a chance. “Sleep is so critical for so many parts of our body and our mind,” says Aric Prather, a sleep scientist at UCSF. It strengthens the immune system and helps regulate metabolism. It can clear out toxins that build up in the brain and prevent neurodegenerative diseases. “Sleep is like the dishwasher of the brain,” Prather explains in WIRED’s latest “Five Levels” video.

Rapid eye movement, or REM, sleep—the phase during which we dream—usually gets the most hype. But Prather says all phases, from the lightest slumber to the deepest unconsciousness, are important processes that allow our brains and bodies to recover from the previous day and can help us learn and remember information better.

Getting rest isn’t always as simple as climbing into bed and shutting off the lights. Circadian rhythms, hormones like melatonin, and even the neurotransmitter dopamine play a role. There’s still a lot scientists don’t understand about what happens when we drift off, but the more we learn, the more important sleep becomes.

Whether a cause or a symptom, abnormal sleep plays a role in diseases like Alzheimer’s and Parkinson’s. Measuring disturbed sleep could be one way to detect the onset of neurodegenerative diseases. Eventually, medicines that help promote more natural sleep cycles could help treat those very diseases. “I’m excited about the future of sleep medicine,” says Prather. Instead of thinking of sleep as a nuisance, maybe we’ll start finally seeing it for what it actually is: a necessity.

Check out the video above. You can also watch the full series on WIRED’s free app for Roku, Apple TV, Android TV and Amazon Fire TV.

More Great WIRED Stories