Sleep & Dreams I: Neurobiology of Sleep

Flashcards covering the neurobiology of sleep, including the two-process model of sleep, brain structures involved, and sleep stages as observed through EEG.

Sleep Deprivation

Routinely sleeping less than 6-7 hours a night, which doubles the risk for cancer, increases the risk for Alzheimer’s Disease, disrupts blood sugar levels, and increases the risk for cardiovascular disease, stroke, and heart failure. Its effects are comparable to a blood alcohol level of about .05%.

Circadian Rhythm

A naturally occurring 24-hour cycle (circa 'around', dian 'day') that dictates the body's natural sleep-wake cycle, which is slightly longer than 24 hours but calibrated by environmental cues like light-dark cycles.

Suprachiasmatic Nucleus (SCN)

The brain's central pacemaker for circadian rhythms, located in the Hypothalamus, responsible for regulating the timing of sleep and wakefulness and the release of Melatonin.

Melatonin

A hormone released by the Pineal gland, regulated by the SCN, which signals the body to sleep during nighttime and stops during daytime.

Homeostatic Sleep Drive (Process S)

The body's intrinsic need for sleep that builds up with prolonged wakefulness, primarily due to the accumulation of adenosine.

Adenosine

A chemical that accumulates in the brain during wakefulness, creating a sleep drive by slowing down neuronal activity.

Caffeine

An adenosine receptor antagonist that temporarily blocks the effects of adenosine, reducing feelings of fatigue.

Two-Process Model of Sleep

Explains the regular sleep-wake cycle as the result of the alignment of two independent processes: Process C (Circadian Rhythm) and Process S (Homeostatic Sleep Drive).

Randy Gardner Experiment

A documented case where a 17-year-old stayed awake for 264 hours and 12 minutes, experiencing significant cognitive and mood disturbances due to extreme sleep deprivation.

Electroencephalography (EEG)

A neuroimaging method that records brain electrical activity using electrodes placed on the scalp, used to identify different brainwave patterns associated with various mental activities and sleep stages.

Beta Waves

Brainwaves associated with an alert, active, awake, and engaged mental state.

Alpha Waves

Brainwaves associated with a state of rest, relaxation, or drowsiness.

Theta Waves

Brainwaves primarily observed during shallow sleep stages (NREM 1 and NREM 2).

Delta Waves

Brainwaves characteristic of deep sleep (NREM 3/4), also known as slow-wave sleep.

NREM Sleep (Non-Rapid Eye Movement Sleep)

Comprises sleep stages 1, 2, and 3/4, characterized by progressively slower brainwave patterns (theta and delta waves) and decreasing mental activity.

REM Sleep (Rapid Eye Movement Sleep)

Also known as paradoxical sleep, characterized by brainwaves similar to an awake state, rapid eye movements, and where most dreaming occurs.

Sleep Spindles

Brief, rapid bursts of brain activity observed during NREM 2 sleep.

K Complex

A large, slow brainwave observed during NREM 2 sleep, often in response to internal or external stimuli.

Sleep Cycle

The recurring progression through NREM and REM sleep stages multiple times throughout the night, typically averaging about 90 minutes per cycle.