Have you ever wondered what happens when we fall asleep. It almost feels as if we skipped through time until we reach the morning. But in reality, there is a lot more that goes on.
During sleep, we cycle through four separate stages which includes 3 different stages of non dreaming ( non rapid eye movement or NREM stage 1,2,3) and one stage of dreaming ( Rapid eye movement or REM). The NREM stages become deeper as they progress. In stage 1 and 2 , we sleep lightly and we can be awakened easily by noises or other disturbances. Stage 3 is a very deep stage of sleep, during which it is very difficult to be awakened. Deep sleep is necessary to feel rested and energetic during the day. REM sleep or the dreaming stage is a more active stage and a memory and emotion consolidating stage that we most typically dream. REM sleep stimulates the brain regions that we use to learn and make memories. During REM our arm and leg muscles are paralyzed so that we cannot “act out” our dreams.
Each cycle of sleep lasts between 90 to 110 minutes. In the first cycle of sleep, deep sleep is about 45 to 60 minutes. It lasts for longer periods in the first half of the night and becomes shorter with each sleep cycle. The first period of REM typically lasts 10 minutes, and becomes longer as night goes by and the final one lasts about an hour.
Infants, unlike adults, commonly enter sleep via REM stage and have a sleep cycle about 45–60 minutes. They spend 50% of their sleep in REM ( more than twice as much as adults) and the REM sleep decreases to approximately 30% at age 1 to 2 years and 20% to 25% at 3 to 5 years of age. Children reach adult values at the adolescence age.
After each sleep cycle, we have a brief awakening and then go back to sleep, repeating the sleep cycle again. There’s usually little to no recollection of those awakening when morning arrives. However, the amounts of wake increases with age.
Practical Point: Desire to sleep through the night without any awakenings is typically unrealistic, especially as we age. Having a better view of what sleep looks like will help us set up realistic expectations
The image is taken from quora.com