We spend a good portion of our life with our eyes shut. For us it’s a simple process: close your eyes, wake up, sneeze, and repeat. And during this daily routine, we often forget how complex it is to sleep.
Sleep is a naturally recurring state of mind and body. Characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and inhibition of nearly all voluntary muscles during rapid eye movement (REM) sleep, and reduced interactions with surroundings.
The most pronounced physiological changes in sleep occur in the brain. The brain uses significantly less energy during sleep than it does when awake, especially non-REM sleep. In areas with reduced activity, the brain restores its supply of adenosine triphosphate (ATP), the molecule used for short-term storage and transport of energy.
Sleep increases the sensory threshold, In other words, a sleeping person perceives fewer stimuli, but can generally still respond to loud noises and other salient sensory events.
During slow-wave sleep, humans secrete bursts of growth hormone. All sleep, even during the day, is associated with the secretion of prolactin.
On average, during an 8-hour sleep, a healthy adult can burn about 500 calories, which is surprisingly more than the number of calories burnt while watching TV for an 8-hour period.
Sleep Cycle - The sleep cycle is an oscillation between the slow-wave and REM (paradoxical) phases of sleep. It is sometimes called the ultradian sleep cycle, sleep–dream cycle, or REM-NREM cycle; to distinguish it from the circadian alternation between sleep and wakefulness. The standard figure given for the average length of the sleep cycle for an adult man is 90 minutes.
Non-REM and REM leep - Sleep is divided into two broad types: non-rapid eye movement (non-REM or NREM) sleep, and rapid eye movement (REM) sleep. Non-REM and REM sleep are so different that physiologists identify them as distinct behavioral states.
Non-REM sleep occurs first and after a transitional period is called slow-wave sleep or deep sleep. During this phase, body temperature and heart rate fall, and the brain use less energy. REM sleep, also known as paradoxical sleep, represents a smaller portion of total sleep time.
Non-REM Sleep - Non-rapid eye movement sleep (NREM), also known as quiescent sleep. The sleep stages are from 1–3, previously were 1– 4. Rapid eye movement sleep (REM) is not included. There are distinct electroencephalographic and other characteristics seen in each stage. Unlike REM sleep, there is usually little or no eye movement. Dreaming is rare during NREM sleep, and muscles are not paralyzed as in REM sleep.
Awake Time - Non-REM sleep is the changeover from wakefulness to sleep. During this short period (lasting several minutes) of relatively light sleep, your heartbeat, breathing, and eye movements slow, and your muscles relax with occasional twitches. Your brain waves begin to slow from their daytime wakefulness patterns.
Light Sleep - Light sleep is a period of non-REM sleep before you enter deeper sleep. Your heartbeat and breathing slow, and muscles relax even further. Your body temperature drops and eye movements stop. Brain wave activity slows but is marked by brief bursts of electrical activity. You spend more of your repeated sleep cycles in stage 2 sleep than in other sleep stages.
Deep Sleep - Deep sleep is the period of non-REM sleep that you need to feel refreshed in the morning. It occurs in longer periods during the first half of the night. Your heartbeat and breathing slow to their lowest levels during sleep. Your muscles are relaxed and it may be difficult to wake you up. Also, brain waves become even slower.
REM Sleep - Rapid movement sleep (REM sleep or REMS) is a unique phase of sleep in mammals and birds, characterized by the random rapid movement of the eyes, low muscle tone throughout the body, and the propensity of the sleeper to dream vividly.
The REM phase is also known as paradoxical sleep (PS) and sometimes desynchronized sleep, because of physiological similarities to waking states, including rapid, low-voltage desynchronized brain waves.
REM sleep first occurs about 90 minutes after falling asleep. Your eyes move rapidly from side to side behind closed eyelids. Mixed frequency brain wave activity becomes closer to that seen in wakefulness. Your breathing becomes faster and irregular, and your heart rate and blood pressure increase to near waking levels.
Most of your dreaming occurs during REM sleep, although some can also occur in non-REM sleep. Your arm and leg muscles become temporarily paralyzed, which prevents you from acting out your dreams. As you age, you sleep less of your time in REM sleep. Memory consolidation most likely requires both non-REM and REM sleep.
Learn those 17 Proven Tips to Sleep Better at Night and you'll enjoy your life with more ease.
Inputs from: Sleep From Wikipedia, the free encyclopedia
Written by - Joshua
Edited by - Dana Asnan
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