What is Sleep?
According to The Free Dictionary:
Sleep is “a natural periodic state of rest for the mind and body, in which the eyes usually close and consciousness is completely or partially lost, so that there is a decrease in bodily movement and responsiveness to external stimuli. During sleep, the brain in humans and other mammals undergoes a characteristic cycle of brain-wave activity that includes intervals of dreaming.”
What Are the Stages of Sleep?
There are four or possibly five stages of sleep:
- Stage one, ofcourse, is the start of the sleeping cycle. It is a light sleep and slowly carries the person from wakefulness into the cycles of sleep as the body relaxes.
- Stage two occurs when the brain waves slow and eye movement stops.
- Stage three is a deeper sleep with delta waves, or very slow brain waves, interspersed with smaller but faster waves.
- Stage four. In stage four, along with stage three, the person is in a deep sleep, one where the person is very hard to wake. The mind and body are so relaxed that some children are susceptible to sleepwalking, nightmares, or wetting the bed.
- NOTE: In 2008, the US sleep profession did away with using stage four and combined it with stage three, which it is so called.
- REM sleep, or rapid eye movement sleep, does not have a stage number and simply includes the initials REM. REM sleep occurs during the latter half of the total sleep cycle, and older adults experience it less frequently than younger people. The rapid eye movement is detected during a sleep study by attaching sensors around the facial muscles controlling eye movement.
Sleep stages are cyclical and happen repeatedly during the night. The time spent in REM sleep lengthens during the night and is the cycle a person is in when they awake.
If the sleep rhythms of a person are upset or disturbed, a person may suffer from sleeping disorders, including sleep apnea, where you stop breathing for more than a few seconds; insomnia, the inability to fall asleep; restless leg syndrome, the irresistible urge to move the legs; or narcolepsy, where sufferers experience sleepiness during the day and may actually fall asleep. These are just a few of the over eighty sleep disorders. If you feel that you do not get sufficient or restful sleep, wake often during the night, or find yourself gasping for breath, it may be time for you to call your local sleep center and ask about a sleep analysis.
-- Important: The Sleep Blog does not provide medical advice, diagnosis, or treatment. Instead, this website provides general information for educational purposes only. Always seek the advice of a qualified health care provider if you have questions or concerns regarding any medical condition or treatment.