Why does rem sleep occur

Factors that influence your sleep-wake needs include medical conditions, medications, stress, sleep environment, and what you eat and drink. Perhaps the greatest influence is the exposure to light. Specialized cells in the retinas of your eyes process light and tell the brain whether it is day or night and can advance or delay our sleep-wake cycle. Exposure to light can make it difficult to fall asleep and return to sleep when awakened. Night shift workers often have trouble falling asleep when they go to bed, and also have trouble staying awake at work because their natural circadian rhythm and sleep-wake cycle is disrupted.

In the case of jet lag, circadian rhythms become out of sync with the time of day when people fly to a different time zone, creating a mismatch between their internal clock and the actual clock.

Your need for sleep and your sleep patterns change as you age, but this varies significantly across individuals of the same age. Babies initially sleep as much as 16 to 18 hours per day, which may boost growth and development especially of the brain.

School-age children and teens on average need about 9. Most adults need hours of sleep a night, but after age 60, nighttime sleep tends to be shorter, lighter, and interrupted by multiple awakenings. Elderly people are also more likely to take medications that interfere with sleep. In general, people are getting less sleep than they need due to longer work hours and the availability of round-the-clock entertainment and other activities.

Many people feel they can "catch up" on missed sleep during the weekend but, depending on how sleep-deprived they are, sleeping longer on the weekends may not be adequate. Everyone dreams. You spend about 2 hours each night dreaming but may not remember most of your dreams. Events from the day often invade your thoughts during sleep, and people suffering from stress or anxiety are more likely to have frightening dreams. Dreams can be experienced in all stages of sleep but usually are most vivid in REM sleep.

Some people dream in color, while others only recall dreams in black and white. Clusters of sleep-promoting neurons in many parts of the brain become more active as we get ready for bed. GABA is associated with sleep, muscle relaxation, and sedation. Norepinephrine and orexin also called hypocretin keep some parts of the brain active while we are awake.

Other neurotransmitters that shape sleep and wakefulness include acetylcholine, histamine, adrenaline, cortisol, and serotonin. Genes may play a significant role in how much sleep we need. Scientists have identified several genes involved with sleep and sleep disorders, including genes that control the excitability of neurons, and "clock" genes such as Per , tim , and Cry that influence our circadian rhythms and the timing of sleep.

Genome-wide association studies have identified sites on various chromosomes that increase our susceptibility to sleep disorders. The point advocated here is that a major function of REM is to help a sleeping brain wake-up. There is also a potential benefit in consolidating certain memories that perhaps cannot be accomplished as well in other stages of sleep.

Then there is the likelihood that REM and dream content can have reward properties. Dog owners, for example, may be justified in the suspicion that their dog sleeps so much because it is bored and looks forward to the adventures, such as chasing deer and catching critters that it has learned can be experienced without effort in REM and its dreams.

This also relates to a basic propensity of brain: stimulus seeking. Advanced animals have an evolved brain that feeds on stimulus. REM is a very convenient way to address that need. Since Stage N3 sleep cortical-column dynamics drive the brain out of the mode required for consciousness, the column circuits have to be re-set, and that apparently can only be accomplished via the ARAS, which in stimulus-absent sleep must be switched on by a much less efficient processes generated within corticothalamic and corticobulbar systems.

REM episodes may be difficult to sustain in early evening because corticifugal influences are apparently less robust than external stimulation. The existence of such supposed changes could be tested with the appropriate electrophysiological approaches. REM could serve to help consciousness-generating systems to reach threshold in the absence of external stimulation.

The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Maquet, P. Functional neuroanatomy of human of rapid-eye-movement sleep and dreaming. During this cycle of your sleep, your eyes will move and dart quickly beneath your eyelids. During REM sleep, your brain activity increases, your pulse quickens, and you have dreams. The first cycle usually lasts about 10 minutes, and each cycle time will increase to as long as one hour in the last phase before you awake. REM sleep is important to your sleep cycle because it stimulates the areas of your brain that are essential in learning and making or retaining memories.

According to the National Institute of Neurological Disorders and Stroke , a study depriving rats of REM sleep significantly shortened their life span, from two or three years to five weeks.

During REM sleep: The eyes and eyelids flutter. Breathing becomes irregular. During REM sleep, it is normal to have short episodes when breathing stops apnea. Related Information Sleep Studies. Credits Current as of: October 26, Top of the page Next Section: Related Information. Previous Section: Related Information Top of the page.