It’s well after midnight. The last rays of sunlight have disappeared below the horizon and the stars are already in their positions, strewn across the night sky. You tear your eyes from the window and glance down at the worksheets you were laboring over, the letters looking more and more like a jumbled mess as your eyelids grow increasingly heavy. Despite the determination to finish the remaining problems, you find yourself unable to keep your eyes open for a second longer, and as you succumb to your body’s demand for sleep, the papers drift out of your memory as your mind drifts off to sleep.

Acquiring a healthy amount of sleep every night is as essential to life as a person’s diet or exercise. While the reasons we need sleep remain an enigma, scientists have made an extensive list of discoveries related to the subject, ranging from seemingly mundane occurrences in the body to odd yet universal sensations that transpire (surface/arise) during slumber.

While the body is asleep, it goes through multiple sleep cycles, each lasting 90 to 110 minutes and consisting of four stages. The first three stages are categorized as NREM sleep, short for non-rapid eye movement, and contain the time it takes for the body to transition from being awake to falling asleep. The fourth stage, REM sleep, short for rapid eye movement, is characterized by twitching of the face and fingers, quick eye movements and the occurrence of dreams.

One of the most well-known sensations is the feeling of falling, formally called a hypnagogic jerk. Hypnagogic jerks occur during NREM sleep. Typically, the body is paralyzed when dreaming starts during REM sleep, but in this case, the body is not on the same page as the brain and a muscle abruptly flexes, followed by the feeling of falling. “It’s more likely to happen when you’re overtired, sleep-deprived or stressed and your brain enters into sleep cycles more aggressively, but your body hasn’t caught up,” said Dr. Christopher Winter, Men’s Health sleep advisor and medical director of the sleep center at Martha Jefferson Hospital in Virginia.

But what if the hypnagogic jerk is reversed, leaving the sleeper’s body paralyzed despite their brain being awake? This is an actual phenomenon known as sleep paralysis, which leaves people unable to speak or move for short periods of time after waking up because their brain has woken up before their body has.

“[Sleep paralysis] only happens to me occasionally, maybe a few times a year,”French teacher, Madame Pummer, said….I have this reoccurring nightmare that someone’s trying to break in and I usually am feeling very confused about whether I’m sleeping or awake. It’s a very vivid dream. Both during the dream and when I wake up, I experience not being able to move any part of my body so it makes the nightmare of trying to defend myself against somebody breaking in very scary…It seems to me like it lasts five to ten minutes,” French teacher, Madame Pummer, said.

Despite these discoveries in the field of sleep, its importance still remains a mystery. However, research on the subject still continues and the future holds the potential to uncover the many unknown secrets surrounding sleep.