The key to a good sleep lies in the first 90 minutes after you fall asleep. A prevailing theory says the depth of sleep in the first 90 minutes is indicative of the quality of your overall sleep for the night because nearly 80% of the growth hormone released during sleep is said to come out during the first 90 minutes of sleep.
Sleep first starts with non-REM (rapid eye movement) sleep (when both the brain and body are asleep), and after about 90 minutes, it switches to REM sleep (when the brain is awake, and the body is asleep). Non-REM sleep and REM sleep are a set of 90 minutes, and this 90-minute cycle repeats four to five times to form a six to eight-hour sleeping. REM sleep is relatively short in the first half of the sleep cycle but becomes longer in the second half. The higher percentage of REM sleep you get as your sleep progresses, the more you prepare your brain to be awake and ready to wake up.
The primary function of the first non-REM sleep
Because of these mechanisms, the first non-REM sleep is the deepest in the overall sleep cycle. And it is at this time that various functions of sleep are at their best.
・Growth hormone, which strengthens muscles and bones and increases metabolism, is released the most.
・Most of the accumulated desire to sleep during the day is released.
・Boost the immune system and prevent diseases.
・Regulate the autonomic nervous system
・Store the memories in the cerebral cortex.
・Delete bad memories.
・Remove waste in brain and condition the brain
If you feel sleepy when you wake up in the morning or don’t feel like you’ve slept much, it often could be the reason that your non-REM sleep is short or you’re not getting deep non-REM sleep. If the first 90 minutes are disrupted, the quality of your overall sleep could be severely harmed.
Deep non-REM sleep regulates your sleep rhythm, your autonomic nervous system, hormonal functioning, and improves your performance the next day. To improve your daily performance, establish regular sleep habits, and a comfortable sleep environment.