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Rapid eye movement sleep (REM sleep or REMS) is a unique phase of sleep in mammals (including humans) and birds, characterized by random rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the sleeper to dream vividly. The core body and brain temperatures increase during REM sleep and skin ...
Young woman asleep over study materials. The relationship between sleep and memory has been studied since at least the early 19th century.Memory, the cognitive process of storing and retrieving past experiences, learning and recognition, [1] is a product of brain plasticity, the structural changes within synapses that create associations between stimuli.
EMG (electromyography) is a crucial method to distinguish between sleep phases: for example, a decrease of muscle tone is in general a characteristic of the transition from wake to sleep, [5] [6] and during REM sleep, there is a state of muscle atonia (paralysis), resulting in an absence of signals in the EMG. [5]
RBD is a sleep disorder characterized by the loss of normal skeletal muscle atonia during REM sleep and is associated with prominent motor activity and vivid dreaming. [6] [2] These dreams often involve screaming, shouting, laughing, crying, arm flailing, kicking, punching, choking, and jumping out of bed.
During a normal night of sleep, a person will alternate between periods of NREM and REM sleep. Each cycle is approximately 90 minutes long, containing a 20-30 minute bout of REM sleep. [7] NREM sleep consists of sleep stages 1–4, and is where movement can be observed. A person can still move their body when they are in NREM sleep.
Conditioned fear, for example, reduces REM sleep whereas auditory stimulation increases it. [4] In humans, models of stress have been closely linked to the context depression. Changes in sleep patterns in depression are very close to those seen in acutely stressed animals; these changes can be used as a predictor for developing depression.
NREM Stage 1 (N1 – light sleep, somnolence, drowsy sleep – 5–10% of total sleep in adults): This is a stage of sleep that usually occurs between sleep and wakefulness, and sometimes occurs between periods of deeper sleep and periods of REM. The muscles are active, and the eyes roll slowly, opening and closing moderately.
REM sleep is decreased during the first half of the sleep period and stage 1 sleep is increased in the second half of the sleep period. [5] Most antidepressants, in particular selective serotonin re-uptake inhibitors (SSRIs), such as citalopram and paroxetine, are potent inhibitors of REM sleep and may also cause a REM rebound on discontinuation.