What is the difference between processes that are awake and those that are asleep

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. Stage 2 non-REM sleep is a period of light 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. Stage 3 non-REM sleep is the period of deep 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 awaken you. Brain waves become even slower. 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.

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. Two internal biological mechanisms —circadian rhythm and homeostasis—work together to regulate when you are awake and sleep.

Circadian rhythms direct a wide variety of functions from daily fluctuations in wakefulness to body temperature, metabolism, and the release of hormones. They control your timing of sleep and cause you to be sleepy at night and your tendency to wake in the morning without an alarm.

Circadian rhythms synchronize with environmental cues light, temperature about the actual time of day, but they continue even in the absence of cues. Sleep-wake homeostasis keeps track of your need for sleep. The homeostatic sleep drive reminds the body to sleep after a certain time and regulates sleep intensity. This sleep drive gets stronger every hour you are awake and causes you to sleep longer and more deeply after a period of sleep deprivation.

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. Learn more about the causes and underlying mechanisms of REM rebound, a phenomenon in which a person temporarily experiences more…. Necessary cookies are absolutely essential for the website to function properly.

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Our editors and medical experts rigorously evaluate every article and guide to ensure the information is factual, up-to-date, and free of bias. Updated October 30, Written by Eric Suni. Medically Reviewed by Ealena Callendar. Related Reading. Sign up below for your free gift. Your privacy is important to us. Was this article helpful? Yes No. Sleep spindles. Current biology : CB, 28 19 , R—R Natural Patterns of Sleep.

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Updated By Eric Suni March 10, Oversleeping By Austin Meadows November 3, By Danielle Pacheco November 11, By Eric Suni November 4, By Eric Suni November 2, After lunch you may be dragging.

Later, your energy levels soar just in time for bed. These cycles are triggered by chemicals in the brain. Chemicals called neurotransmitters send messages to different nerve cells in the brain. Nerve cells in the brainstem release neurotransmitters. These include norepinephrine, histamine, and serotonin.

Neurotransmitters act on parts of the brain to keep it alert and working well while you are awake. Other nerve cells stop the messages that tell you to stay awake. This causes you to feel sleepy. One chemical involved in that process is called adenosine. Caffeine promotes wakefulness by blocking the receptors to adenosine.

Adenosine seems to work by slowly building up in your blood when you are awake. This makes you drowsy. While you sleep, the chemical slowly dissipates. Two body processes control sleeping and waking periods.