EXSC Lecture 10: Exercise & Sleep

Comprehensive vocabulary flashcards covering the neurobiology of sleep, sleep staging, regulation mechanisms, sleep disorders, and the experimental effects of acute and chronic exercise on sleep architecture.

Sleep

A daily, reversible behavior involving disengagement from, and reduced sensory responsiveness to, the environment, occurring in a stereotypic posture and resulting in characteristic electroencephalographic (EEG) patterns.

Nathaniel Kleitman

A pioneering sleep researcher who discovered rapid eye movement (REM) sleep in the 1950s.

Electroencephalogram (EEG)

A physiological recording method used to detect and measure brain wave activity.

Electrooculogram (EOG)

A physiological recording technique used to monitor and measure eye movements during wakefulness and sleep.

Electromyogram (EMG)

A physiological recording technique used to measure electrical activity and muscle tension in skeletal muscles.

REM Sleep

A distinct sleep stage characterized by high central nervous system activity with a wake-like tonic EEG, phasic rapid eye movements, complete inhibition of most skeletal muscle EMG (interspersed with phasic twitches), and dreaming.

William Dement

A leading authority on sleep science who founded the first sleep research center at Stanford University.

Pons (in REM Regulation)

A brainstem structure that triggers REM sleep alongside neighboring structures while sending descending inhibitory signals to shut off spinal cord motor neurons.

Nucleus Reticularis Pontis Oralis/Caudalis (RPO/RPC)

The most critical anatomical site within the pons for the production of REM sleep, containing neurons that primarily utilize acetylcholine as their neurotransmitter.

Dorsal Raphe and Locus Coeruleus

Brainstem nuclei utilizing serotonin ($5\text{-HT}$) and norepinephrine ($\text{NE}$), respectively, that act to turn off or suppress REM sleep.

Slow Wave Sleep (SWS)

Deep, restorative non-REM sleep comprising Stage 3 and Stage 4, defined electrophysiologically by high-amplitude, low-frequency delta waves ($< 3\text{ /sec}$).

Beta Waves

High-frequency brain waves operating at $> 12\text{ /sec}$, characteristic of alert wakefulness.

Alpha Waves

Brain waves with an oscillation frequency of $8\text{--}12\text{ /sec}$, characteristic of relaxed wakefulness with eyes closed; higher alpha levels during wake indicate reduced neural network activation.

Theta Waves

Brain waves with a frequency of $3\text{--}7\text{ /sec}$, prominently observed during light Stage 1 non-REM sleep.

Delta Waves

Low-frequency brain waves operating at $< 3\text{ /sec}$, reflecting minimal activation and high synchronization of cortical neural networks during slow wave sleep.

Reticular Formation

A core brainstem network whose activation drives wakefulness and cortical arousal, while its deactivation facilitates the generation of non-REM sleep.

Basal Forebrain

The most effective anatomical site in the brain for the induction of non-REM sleep via electrical and chemical stimulation.

Preoptic-Anterior Hypothalamus

A hypothalamic region containing temperature-sensitive neurons that project to the basal forebrain and are hypothesized to play a critical role in controlling slow wave sleep.

Benzodiazepines

Hypnotic and anti-anxiety medications (such as Valium) that promote sedation by enhancing the inhibitory activity of $GABA_A$ receptors, which are densely distributed in the amygdala, hypothalamus, periaqueductal gray (PAG), and hippocampus.

Adult Sleep Architecture

The normal structural progression of sleep, characterized by sleep onset in $< 20\text{ minutes}$, initiation in Stage 1, NREM/REM cycles alternating every $\thicksim 90\text{ minutes}$, majority of SWS in the first $3$ cycles, majority of REM in the final third of the night, and total sleep time averaging $6.5\text{ to }7.5\text{ hours}$.

Process S

The homeostatic sleep drive that accumulates monotonically across the period of prior wakefulness and dissipates during sleep, directly determining the quantity of slow wave sleep.

Process C

The endogenous circadian pacemaker that oscillates independently of prior wakefulness, regulating overall sleep duration, alertness fluctuations, and the timing of the first REM period.

Two-Process Model of Sleep Regulation

The theoretical model proposed by Borbély (1982) explaining sleep propensity through the nonlinear interaction of the homeostatic sleep drive (Process S) and the circadian rhythm (Process C).

Suprachiasmatic Nucleus (SCN)

The master circadian pacemaker in the anterior hypothalamus that receives photic input from the retina via glutamatergic signaling to synchronize biological rhythms with environmental day-night cycles.

Metabolic Waste Clearance ('Brainwashing')

A hypothesized primary function of sleep whereby interstitial fluid channels expand during sleep, allowing cerebrospinal fluid to flush out neurotoxic metabolic byproducts from the brain.

Retrograde CSF Flow Waves

Pulsatile waves of cerebrospinal fluid in the fourth ventricle that reverse direction during slow wave sleep, tightly coupled to slow-wave neural activity and low-frequency oscillations in cerebral blood volume.

Sleep Onset Insomnia

A clinical pattern of insomnia characterized by a prolonged latency and marked difficulty in falling asleep at the beginning of the sleep period.

Sleep Maintenance Insomnia

A pattern of insomnia marked by frequent awakenings or extended periods of wakefulness throughout the middle of the sleep period.

Early Morning Awakening Insomnia

A pattern of insomnia characterized by waking up prematurely at the end of the night and inability to fall back asleep.

Sleep Apnea

A common sleep disorder affecting approximately $24\%$ of middle-aged men and $9\%$ of middle-aged women, characterized by habitual loud snoring, repeated cessation of breathing during sleep, and excessive daytime sleepiness.

Acute Exercise Effect on REM Latency

A significant biological response following a single bout of exercise in which the onset of REM sleep is delayed by an average effect size of $d = 0.52$ (a mean delay of $13.1\text{ minutes}$).

Circadian Phase Delay (from Exercise)

A shift in the human circadian timing system that occurs when a prolonged bout of exercise is performed approximately $6\text{ to }10\text{ hours}$ before one's habitual wake time.

Delayed-Onset Muscle Soreness (DOMS) and Sleep

The experimental finding that unaccustomed eccentric exercise producing muscle soreness does not cause widespread sleep disturbances and slightly improves total sleep time.

Cardiorespiratory Fitness Decline and Incident Sleep Complaints

The prospective epidemiological relationship demonstrating that each $1\text{-minute}$ decline in treadmill endurance between ages $51$ and $56$ increases the odds of incident physician-reported sleep complaints by $1.7\%$ in men and $1.3\%$ in women.