What is REM Sleep.

Rapid Eye Movement (REM) sleep is also called the active sleep or paradoxical sleep. This is the part of sleep cycle when you actively dream and the eye balls move randomly back and forth, which is why it is called rapid eye movement sleep. The sleep cycle is consists NREM sleep stages and the REM sleep stage. NREM stage is explained in NREM sleep.

Image showing NREM and REM sleep stages.

Click on image to enlarge

REM Sleep Duration.

In most human adults, REM sleep stage accounts for 20% to 25% of the total sleep time. If you sleep for about 7 to 8 hours, about an hour and a half is spent in REM sleep stage. This stage occurs about 70 to 90 minutes after falling asleep. This sleep is also called the active sleep and is characterized by high frequency low amplitude alpha waves on EEG.

During the first sleep cycle, the REM sleep stage is shorter with more time in deep sleep, but as morning approaches, the REM sleep stage becomes longer and the stages of deep sleep become shorter. Each subsequent sleep cycle therefore has more REM sleep and less deep sleep. During the first sleep cycle, the REM sleep may only be of 10 minutes duration, while in the morning during the last cycle the REM cycle may last for 90 minutes.

What Happens in REM Sleep.

In this stage of REM sleep,

• Brain activity is increased researchers found activity in areas of the brain that control sight, touch, hearing, smell, arousal, transitions from sleep to wakefulness and balance and body movement.

• You dream actively and may not remember the dreams in the morning when you wake up,
• Sensory information of the outside world is shut off,
• There is rapid back and forth movement of the eyes,
• Breathing is shallow, irregular and faster than normal,
• Heart rate and blood pressure increase,
• Arms and legs muscles are temporarily paralyzed with loss in muscle tone.
• Men may experience erections during this stage.

The brain activity in this stage is quite intense and is as much as during waking hours. Because of this paradox of voluntary muscles becoming paralyzed in spite of increased brain activity, this stage of REM sleep is also called the paradoxical sleep.

The REM sleep paralysis is caused by release of glycine, an amino acid, from the brain stem into the motoneurons. Motoneurons are neurons which send impulses from the brain or spinal cord to the muscles of the body. This is probably nature’s way of ensuring that we do not act out our dreams.

Factors That Influence REM Sleep.

The duration and quickness of the onset of REM sleep depends on physical and psychological factors.

• People who sleep less or are sleep deprived move to stage 3 of NREM sleep and REM sleep faster than people who sleep well.

• Depression: People who suffer from depression have shorter REM sleep duration than normal.
• Certain Antidepressants: Depressed people who take treatment for their depression with antidepressants like Prozac have longer REM sleep.
• REM sleep behavioral disorder (RBD): In people with REM sleep behavioral disorder,  there is delayed onset of REM sleep and the muscles do not get paralyzed. Such people with REM disorder therefore, often tend to act out their dreams which are intense, vivid and violent. Such actions include talking, yelling, punching, kicking, jumping from the bed, grabbing, etc. Acute form of such cases may be seen in narcolepsy, withdrawal alcohol syndrome and in patients on sedative-hypnotic drugs. REM sleep disorder  is more common in middle-aged to elderly men
• Age: Babies and small children have the highest proportion of REM sleep. A newborns baby spends more than 80% of its total sleep time in the REM sleep stage. This proportion decreases with adolescence. Old age is associated with the lengthening of the REM sleep.

 Importance of REM Sleep.

REM sleep is important to preserve long-term memories. If a person is awakened during this stage of REM sleep, the next sleep does not follow the normal pattern but begins with REM sleep stage till the previous night’s REM sleep time is made up.

REM sleep function is still not clear. Only theories abound.

Just as deep sleep rejuvenates the body, REM sleep refreshes and renews the mind. REM sleep stages are longer in the morning and therefore try to prolong sleep a little extra without disturbance in the morning.

• This stage plays a key role in learning and developing, improving and consolidating memory.
• It builds up and processes the information gathered.
• Neural connections are formed which strengthen memory.
• Lack of this sleep harms the ability of a person to learn and grasp new things. It can also adversely affect your performance, mood and health.
• Supply of neurotransmitters such as serotonin and dopamine  is maintained which helps to give a boost to your mood during the day.

Related posts:

1. NREM Sleep – Non Rapid Eye Movement Sleep.
2. Deep Sleep – An Important Sleeping Stage.
3. Polysomnography – A Sleep Study.
4. Over The Counter and Natural Sleep Aids to Help You Sleep.
5. How You Fall Asleep.
6. Proper Bedroom and Bed to Sleep Better.
7. Cognitive Behavioral Therapy – An Effective Sleep Treatment.
8. How is Sleep Apnea Diagnosed.