REM sleep is the portion of sleep when there are rapid eye movements (REMs).
Dreams occur during REM sleep. We typically have 3 to 5 periods of REM sleep per night. They occur at intervals of 1-2 hours and are quite variable in length. An episode of REM sleep may last 5 minutes or over an hour. About 20% of sleep is REM sleep. If you sleep 7-8 hours a night, perhaps an hour and half of that time, 90 minutes, is REM sleep.
REM sleep is characterized by a number of other features including rapid, low-voltage brain waves detectable on the electroencephalographic (EEG) recording, irregular breathing and heart rate and involuntary muscle jerks.
By contrast, NREM (non-REM) sleep is dreamless sleep. During NREM, the brain waves on the EEG are typically slow and of high voltage, the breathing and heart rate are slow and regular, the blood pressure is low, and the sleeper is relatively still. NREM sleep is divided into 4 stages of increasing depth of sleep leading to REM sleep. About 80% of sleep is NREM sleep. If you sleep 7-8 hours a night, all but maybe an hour and a half is spent in dreamless NREM sleep.
- Sleep-disordered breathing
A condition characterized by repeated episodes of hypopnea (underbreathing) and apnea (not breathing) during sleep. A significant proportion of adults are thought to experience sleep-disordered breathing. Sleep-disordered breathing can cause temporary elevations in blood pressure in association with lowered blood oxygen levels and may cause elevated blood pressure during the daytime and, in time, sustained […]
- Sleeping disease
A neurological disorder marked by a sudden recurrent uncontrollable compulsion to sleep. Also known as narcolepsy. The disorder is often associated with cataplexy (a sudden loss of muscle tone and paralysis of voluntary muscles associated with a strong emotion), sleep paralysis (immobility of the body that occurs in the transition from sleep to wakefulness), what […]
Ensure that the sleepwalker is in a safe room for walking and cannot accidentally fall through an open window or down stairs. Some types of sleepwalking are related to seizure disorders, bipolar disorders, and other neurological conditions, but most cases are transitory and due to unknown causes. Also known as somnambulism.
- Sliding hiatal hernia
Hiatal hernias are categorized as being either sliding or para-esophageal. Sliding hiatal hernias are those in which the junction of the esophagus and stomach, referred to as the gastro- esophageal junction, and part of the stomach protrude into the chest. The junction may reside permanently in the chest, but often it juts into the chest […]
- Slipped disc
Rupturing of the tissue that separates the vertebral bones of the spinal column. The center of the disc, which is called the nucleus, is soft, springy and receives the shock of standing, walking, running, etc. The outer ring of the disc, which is called the annulus (Latin for ring), provides structure and strength to the […]