Doctors Answers (2)
When you sleep, your body rests and restores its energy levels. Sleep is an active state that affects both your physical and mental well-being. Sleep is prompted by natural cycles of activity in the brain and consists of two basic states: rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep, which consists of Stages 1 through 4. Each stage can last from 5 to 15 minutes. A completed cycle of sleep consists of a progression from stages 1-4 before REM sleep is attained, then the cycle starts over again. During sleep, the body cycles between non-REM and REM sleep. Typically, people begin the sleep cycle with a period of non-REM sleep followed by a very short period of REM sleep. Dreams generally occur in the REM stage of sleep.
A complete sleep cycle is 90-110 minutes on average and most people have 4-6 of these cycles through the night. Stage 1-3 and REM sleep constitute the cycle. The first half of the night has a higher proportion of deep (recuperating) sleep while that decreases by the second half where REM sleep increases. The deep sleep is needed to repair the body and grow. REM sleep is a lighter sleep and is needed for memory and concentration. This is primarily where people remember their dreams. If you're continually feeling tired in the morning, there is always the possibility that you're waking up during a deeper stage of sleep. You may also be lacking the deep sleep if your sleep is disrupted and you may be fluttering in a lighter stage for the majority of the night. A sleep study is a good place to start to analyze your sleep patterns.
