Stages of Sleep

There are five stages of sleep that individuals go through when they lay down at night. A full cycle of sleep requires typically ninety to one hundred and ten minutes. The stages of sleep include one, two, three, four, and REM, or rapid eye movement sleep.

 The first stage of sleep :

proves to be a lighter sleep. The individual is easily awakened as the person drifts in and out of sleep. During this first stage of sleep, the person’s muscle activity slows down while the eyes slowly move. In this sleep stage, numerous individuals feel a sense of falling that leads to unexpected contractions of the muscles.

Stage two sleep:

 involves the slowing down of the brain wave activity. This is interrupted by a sudden surge of quick brain waves once in a while. Eye movements cease in this stage.

Stage three of sleep:

 involves another change in the brain waves. Delta waves, which are very slow brain waves, appear. They become interspersed with faster and smaller waves.

Stage four is known for almost entirely delta wave production. Both stages three and four are called the stages of deep sleep. People are not easily woken up from these sleep stages. Muscle activity and eye movement cease altogether. In these stages of sleep, children sometimes undergo night terrors or sleep walking. Occasionally they wet the bed here too.

 REM sleep is characterized by a more shallow, irregular, and fast breathing. The limb muscles cannot be moved, and eyes twitch rapidly. In this stage of sleep, the brain waves rise to levels only seen when the individual is normally awake. Blood pressure goes up, the rate of heart beat increases, men have erections, and the body loses part of its temperature regulating capabilities. In this stage, the majority of dreams happen. When people are wakened in REM sleep, they are able to remember their dreams. Typically, persons undergo from three to five different REM sleep intervals every night.

 REM sleep amounts vary based on a person’s age. Babies spend practically fifty percent of their sleep in the REM stage of sleep. Adults on the other hand, are in stage two of sleep about half of their time, while they spend twenty percent of sleep time in REM and the remaining thirty percent in the three other stages. As adults grow older, they spend less and less time in the REM stage of sleep.

 In the different stages of sleep, the brain waves given off vary significantly. Scientists believed until 1953 that brain activity stopped when a person slept. From that point on, with the discovery of REM sleep, scientists have unraveled the different stages of sleep as they pertain to brain activity. The different wave lengths of the five stages of sleep are detailed below, as follows:

 

Stg.        Frequency-Hz   Amp. (micro Volts)         Waveform type

awake  15-50     <50       

pre-sleep            8-12       50           alpha rhthym

1             4-8         50-100  theta

2             4-15       50-150  splindle waves

3             2-4         100-150                spindle waves and slow waves

4             0.5-2      100-200                slow waves and delta waves

REM      15-30     <50       

The first several cycles of sleep every night provide comparatively shorter REM stages of sleep. At this point, there are longer periods of deeper sleep. As the night grows later, the REM sleep stage grows longer and the amount of deep sleep lessons.