Sleep is a period of inactivity that helps regulate the brain and keeps it working at the optimal level. Therefore, the most vital function of sleep is the maintenance of the brain. However, sleep is additionally essential for several other critical functions, both physically and mentally.
The need for sleep varies greatly throughout life and differs from person to person, but most adults sleep on an average of 7-8 hours every day. The total amount of time you spent sleeping also depends on individual perception. However, it would help if you sleep such a lot that you feel fresh and at ease during the day, to prevent falling asleep involuntarily.
•Stages of Sleep.
Sleep consists of two broad phases: The non-REM and paradoxical (REM) sleep characterized by rapid eye movements(REM).
Non-REM sleep involves three stages before it transitions to paradoxical sleep, which is also called dream sleep. Both phases of sleep form the sleep cycle. The sleep cycle lasts for 90-120 minutes in adults, and the cycle is repeated up to 5 times during the night.
Stage 1: This stage is characterized by slipping in and out of sleep, and you can be easily awakened. This stage lasts for a couple of minutes and is taken into account a transitional phase between being awake and sleeping.
Stage 2: The sleep is light and lasts for 15-30mins, and you will be stimulated more to be woken up than stage 1.
Stage 3: The sleep is deep, and it’s also called the slow wave-sleep because, during this stage, the electrical activity in the brain slows down gradually. Deep sleep is the most prominent during the first three hours of sleep.
In the paradoxical (REM) sleep, the brain activity is like when you are awake. Adults spend fifty percent of the total sleep time in stage 2, and twenty percent in paradoxical sleep. Therefore, the remaining thirty percent is spent in stages 1 and 3.
Studies show that the brain areas that control emotions, decision-making, and social functions are impaired during deep sleep.
The paradoxical sleep episodes get longer as the night progresses, and this sort of sleep stimulates a part of the brain that’s active during learning. Thus it is vital for learning and remembering new things.