Sleep Science and REM Sleep Characteristics

A stage of sleep characterized by rapid eye movements, muscle paralysis, high brain activity, and increased autonomic nervous system variability.

A sudden, sharp waveform that occurs spontaneously in stage 2 sleep, sometimes triggered by noises.

A burst of 11-15Hz waves that occur in stage 2 sleep, lasting 0.5-2 seconds. Their frequency is correlated with higher IQ scores.

The deepest stage of sleep, characterized by slow-wave activity (delta waves) and EEG synchrony.

The initial stages of sleep before REM occur, including stage 1, 2, and 3.

The sleep cycle, from initial stage 1 to stage 3 and back to emergent stage 1, repeating throughout the night.

The tendency for dreams to be more coherent and story-like when awoken from REM sleep.

The phenomenon of a person being easily aroused by meaningful stimuli during REM sleep.

Memories that can be consciously recalled and described, like past events or learned facts. These memories are often strengthened during slow-wave sleep.

Memories acquired through experience, often without conscious effort, like learning to ride a bike or recognizing a familiar face. These memories are typically strengthened during REM sleep.

A cycle of physiological and behavioral processes that repeats roughly every 24 hours, influenced by environmental cues like light.

The synchronization of a biological rhythm, like the sleep-wake cycle, to an environmental cue, like daylight.

Environmental cues, like light or temperature changes, that help synchronize the circadian rhythm.

Circadian rhythms that persist even in the absence of external cues, like light or darkness.

When the sleep-wake cycle and body temperature cycle become desynchronized, typically occurring in controlled laboratory environments with constant conditions.

Disruption of the circadian rhythm caused by rapid travel across time zones, leading to sleep disturbances and fatigue.

A disruption of the natural sleep-wake cycle due to working shifts that do not align with the body's natural rhythm.

A dedicated region in the brain's hypothalamus that serves as the master clock controlling the circadian rhythm, receiving light information from the eyes.

A specialized photochemical found in retinal ganglion cells that transmits light information from the eyes directly to the SCN, influencing the circadian clock.

The pathway that transmits light information from the retina to the SCN, helping adjust the circadian clock.

Biological processes that naturally occur over a 24-hour cycle, even in the absence of environmental cues, indicating the presence of an internal timing mechanism.

Circadian genes are responsible for the rhythmic patterns of biological processes like sleep-wake cycles. They control the transcription of proteins, creating a 24-hour cycle.

The Suprachiasmatic Nucleus (SCN) is a tiny region in the hypothalamus that acts as the body's internal clock. It regulates the timing of various physiological processes, including sleep cycles.

The SCN receives light signals from the eyes and uses them to synchronize its internal rhythm with the external environment. This process is known as entrainment.

Melatonin is a hormone secreted by the pineal gland, primarily during darkness. It plays a crucial role in regulating sleep-wake cycles and other seasonal processes.

Melatonin can influence the sensitivity of the SCN to external cues, like light, and can directly modify circadian rhythms.

The locus coeruleus (LC) is a brain region that releases norepinephrine, a neurotransmitter involved in arousal and wakefulness. Its activity is high during wakefulness and reduced during sleep.

Acetylcholine (ACh) is a neurotransmitter that plays a role in arousal and REM sleep. Its levels are high during wakefulness and REM, but lower during slow-wave sleep.

Advanced sleep phase syndrome is characterized by an early sleep and wake cycle, often caused by a mutation affecting the SCN's sensitivity to light.

A nucleoside neuromodulator released by astrocytes during increased brain activity, inhibiting neural activity and promoting sleep.

A sleep disorder where breathing repeatedly stops during sleep, leading to awakenings and daytime sleepiness.

A sleep disorder caused by obstruction of the respiratory passages during sleep, often associated with snoring.

A sleep disorder where the central nervous system fails to stimulate respiration during sleep.

A rare, inherited sleep disorder characterized by progressive insomnia leading to death.

A sleep disorder where involuntary limb movements occur during sleep, often involving leg twitches.

A sleep disorder characterized by an irresistible urge to move the legs, often accompanied by discomfort or tension.

All sleep disorders related to difficulty initiating and maintaining sleep.

A region in the brainstem responsible for general arousal and wakefulness, often called the "reticular activating system".

The preoptic area (POA) is a brain region thought to promote sleep. It inhibits the activity of arousal neurons.

The locus coeruleus (LC) is a brain region heavily involved in wakefulness and alertness. Its activity is high when you're awake.

The raphe nuclei are a group of brain structures that release serotonin, a neurotransmitter associated with mood, sleep, and appetite. They are less active during sleep.

A set of neurons in the hypothalamus that are highly active during wakefulness. They are involved in promoting wakefulness.

A sleep stage characterized by slow brain waves, deep relaxation, and reduced muscle activity. It is the deepest stage of sleep.

A general term for the various brain regions and mechanisms that regulate sleep and wakefulness.