According to the sleep foundation, when you sleep, you often go through several rounds of the sleep cycle, which in most cases is usually four to six. Of course, it varies from individual to individual, so think about it. To be rested, you need more than two rounds of sleep; how many do you think you get in a night? Moreover, sleep cycles vary between 90-120 minutes, the shortest being the first round of sleep. Explained below are the four stages of sleep.

The Four Stages of Sleep

There are four stages of sleep, one being REM sleep or rapid eye movement and three non-REM stages of sleep. It is your brain activity that determines the stages of sleep, each having its own characteristics.

Stage 1 (Light Sleep):  your brain slows down, you feel drowsy, and your breathing becomes regular. Your relaxed brain frequency transitions to a lower frequency. Your body still retains muscle tone.

Stage 2 (Light Sleep): You are about to transition into deep sleep, and your body temperature and heart rate decrease.

Stage 3 (Deep Sleep): The most important stage of sleep, your brain waves at this stage experience delta waves. Delta waves are the slowest recorded brain waves in humans, commonly experienced by babies and associated with the deepest levels of relaxation and restorative, healing sleep. Now you know why they call it “SLEEPING LIKE A BABY.” Waking up in this stage, you could experience fogginess and poor cognitive performance, so think about what happens when you don’t get this stage of sleep daily. Yes, you might just become a zombie, not the man-eating kind, but you certainly won’t be nice to be around; you’d be grouchy.

In deep sleep, your body heals and repairs itself releasing growth hormone. Your immunity is boosted, your bones, muscles and tissues regenerate as well. More importantly, deep sleep contributes to learning, cognitive function, and brain development. Now you know why stage 3 is so important?

Stage 4 (REM sleep): Your breathing is irregular, your heart rate rises, and you lose muscle tone, but you could be almost awake. REM is when you usually dream, and  occurs in the second half of the night. This is why most people tend to dream a lot in the wee hours of the morning or 3am, the witching hour. Now here’s the thing. REM sleep contributes to dreaming, memory, emotional processing, and healthy brain development. Lack of REM sleep can also affect mood and your ability to learn.

Among the stages of sleep, each one is important, but stage 3 is the most important, without which you don’t really sleep. According to an exciting study in 2013, it was found that the brain has a waste management plumbing system that flushes out toxins during sleep. So, I guess you need at least 4 rounds of sleep; Calculate that by the minimum 90 minutes; that’s 6 hours of sleep a day. Now watch the video below from sleep foundation.org which explains why deep sleep is so important.