There are different stages of sleep when you close your eyes. Tight now they are divided into two stages the REM, which is Rapid Eye Movement and NREM, which is Non Rapid Eye Movement. REM sleep is defined by the characteristics of an EEG, which measures the loss of skeletal muscle tone and sympathetic nervous system activity sleep patterns. NREM sleep is regulated by what is called the parasympathetic nervous system activity.

Non REM sleep occurs for almost 75% of the time you are sleeping. There are four stages of NREM sleep. Stage one is the almost appearance of the alpha waves which are seen when the subject is awake and the theta waves which appear in the sleep stage. This first stage is commonly known as drowsy or nodding off sleep. These waves appear when the subject is at the stage of sleep onset. Stage two is called the sleep spindles this is the stage of sleep when the outside environment disappears. Which means, is when you fall asleep but you are not yet into a deep sleep.

Stage three sees the appearance of delta waves or delta rhythms; this is the part of sleep where the brain waves are slow and is making the transitions into the final stage of NREM. Stage four is absolute delta wave sleep. This accounts for only 15% of the sleep time. It is also described as the deepest stage of sleep. In this stage a person suffer from nightmares, talking in your sleep and bed-wetting.

Now you have entered REM sleep, this is where the dreaming starts. The strange and random dream happen in this stage. You can still dream in the stages of NREM but the deepest sleep happens here in the REM.