REM sleep REM sleep (Dream sleep) – About 70 to 90 minutes after falling asleep, you enter REM sleep, where dreaming occurs. Eyes move rapidly. Breathing is shallow. Heart rate and blood pressure increase. Arm and leg muscles are paralyzed. Just as deep sleep renews the body, REM sleep renews the mind. REM sleep plays a key role in learning and memory. During REM sleep, your brain consolidates and processes the information you’ve learned during the day, forms neural connections that strengthen memory, and replenishes its supply of neurotransmitters, including feel-good chemicals such as serotonin and dopamine that boost your mood during the day.View full size

REM sleep

REM sleep (Dream sleep) – About 70 to 90 minutes after falling asleep, you enter REM sleep, where dreaming occurs. Eyes move rapidly. Breathing is shallow. Heart rate and blood pressure increase. Arm and leg muscles are paralyzed.

Just as deep sleep renews the body, REM sleep renews the mind. REM sleep plays a key role in learning and memory. During REM sleep, your brain consolidates and processes the information you’ve learned during the day, forms neural connections that strengthen memory, and replenishes its supply of neurotransmitters, including feel-good chemicals such as serotonin and dopamine that boost your mood during the day.
Non-REM sleep Stage N1 (Transition to sleep) – This stage lasts about five minutes. Eyes move slowly under the eyelids, muscle activity slows down, and you are easily awakened. Stage N2 (Light sleep) – This is the first stage of true sleep, lasting from 10 to 25 minutes. Eye movement stops, heart rate slows, and body temperature decreases. Stage N3 (Deep sleep) – You’re difficult to awaken, and if you are awakened, you do not adjust immediately and often feel groggy and disoriented for several minutes. In this deepest stage of sleep, brain waves are extremely slow. Blood flow is directed away from the brain and towards the muscles, restoring physical energy. View full size

Non-REM sleep

Stage N1 (Transition to sleep) – This stage lasts about five minutes. Eyes move slowly under the eyelids, muscle activity slows down, and you are easily awakened.

Stage N2 (Light sleep) – This is the first stage of true sleep, lasting from 10 to 25 minutes. Eye movement stops, heart rate slows, and body temperature decreases.

Stage N3 (Deep sleep) – You’re difficult to awaken, and if you are awakened, you do not adjust immediately and often feel groggy and disoriented for several minutes. In this deepest stage of sleep, brain waves are extremely slow. Blood flow is directed away from the brain and towards the muscles, restoring physical energy.

Some of your most refreshing sleep occurs during deep sleep. Although such sleep’s true effects are still being studied, it is generally considered a restorative period for the brain. Getting good, restorative sleep is not just a matter of spending enough hours in bed. The amount of time you spend in each of the stages of sleep matters. A normal adult spends approximately 50 percent of total sleep time in stage 2 sleep, 20 percent in REM sleep, and 30 percent in the remaining stages, including deep sleep. Each stage of sleep in the sleep cycle offers benefits to the sleeper. However, deep sleep (stages 3 and 4) and REM sleep are particularly important. View full size

Some of your most refreshing sleep occurs during deep sleep. Although such sleep’s true effects are still being studied, it is generally considered a restorative period for the brain. Getting good, restorative sleep is not just a matter of spending enough hours in bed. The amount of time you spend in each of the stages of sleep matters.

A normal adult spends approximately 50 percent of total sleep time in stage 2 sleep, 20 percent in REM sleep, and 30 percent in the remaining stages, including deep sleep.

Each stage of sleep in the sleep cycle offers benefits to the sleeper. However, deep sleep (stages 3 and 4) and REM sleep are particularly important.

There are two main types of sleep: Non-REM (NREM) sleep consists of four stages of sleep, each deeper than the last. REM (Rapid Eye Movement) sleep is when you do most active dreaming. Your eyes actually move back and forth during this stage, which is why it is called Rapid Eye Movement sleep. View full size

There are two main types of sleep:

Non-REM (NREM) sleep consists of four stages of sleep, each deeper than the last.

REM (Rapid Eye Movement) sleep is when you do most active dreaming. Your eyes actually move back and forth during this stage, which is why it is called Rapid Eye Movement sleep.

At night, your body responds to the loss of daylight by producing melatonin, a hormone that makes you sleepy. During the day, sunlight triggers the brain to inhibit melatonin production so you feel awake and alert.View full size

At night, your body responds to the loss of daylight by producing melatonin, a hormone that makes you sleepy. During the day, sunlight triggers the brain to inhibit melatonin production so you feel awake and alert.

Your internal 24-hour sleep-wake cycle, otherwise known as biological clock or circadian rhythm, is regulated by processes in the brain that respond to how long you’ve been awake and the changes between light and dark.View full size

Your internal 24-hour sleep-wake cycle, otherwise known as biological clock or circadian rhythm, is regulated by processes in the brain that respond to how long you’ve been awake and the changes between light and dark.

A sleep debt can be repaid—though it won’t happen in one extended snooze marathon. Tacking on an extra hour or two of sleep a night is the way to catch up. Go to bed when you are tired, and allow your body to wake you in the morning (no alarm clock allowed). View full size

A sleep debt can be repaid—though it won’t happen in one extended snooze marathon. Tacking on an extra hour or two of sleep a night is the way to catch up. Go to bed when you are tired, and allow your body to wake you in the morning (no alarm clock allowed). 

People accumulate sleep debt surreptitiously. Studies show that such short-term sleep deprivation leads to a foggy brain, worsened vision, impaired driving, and trouble remembering. Long-term effects include obesity, insulin resistance, and heart disease. And most Americans suffer from chronic deprivation. Ref: William C. Dement, founder of the Stanford University Sleep Clinic. View full size

People accumulate sleep debt surreptitiously. Studies show that such short-term sleep deprivation leads to a foggy brain, worsened vision, impaired driving, and trouble remembering. Long-term effects include obesity, insulin resistance, and heart disease. And most Americans suffer from chronic deprivation.

Ref: William C. Dement, founder of the Stanford University Sleep Clinic. 

Sleep debt is the difference between the amount of sleep you should be getting and the amount you actually get. It’s a deficit that grows every time we skim some extra minutes off our nightly slumber.View full size

Sleep debt is the difference between the amount of sleep you should be getting and the amount you actually get. It’s a deficit that grows every time we skim some extra minutes off our nightly slumber.