Sleep-Wake Disorders

(N1)

is a transition from wakefulness to sleep and occupies about 5% of time spent asleep in healthy adults.

N2

characterized by specific electroencephalographic waveforms (sleep spindles and K complexes), occupies about 50% of time spent asleep.

N3

the deepest level of sleep and occupies about 20% of sleep time in healthy, younger adults

Sleep continuity

refers to the overa l balance of sleep and wakefulness during a night of sleep. “Better” sleep continuity indicates consolidated sleep with little wakefulness or fragmentation; “worse” sleep continuity indicates disrupted sleep with more wakefulness and fragmentation

sleep latency

the amount of time required to fall asleep

wake after sleep onset

—the amount of awake time between initial sleep onset and final awakening

Insomnia Disorder

A. A predominant complaint of dissatisfaction with sleep quantity

or quality, associated with one (or more) of the folowing

symptoms:

1. Difficulty initiating sleep. (In children, this may manifest as

difficulty initiating sleep without caregiver intervention.)

2. Difficulty maintaining sleep, characterized by frequent

awakenings or problems returning to sleep after

awakenings. (In children, this may manifest as difficulty

returning to sleep without caregiver intervention.)

3. Early-morning awakening with inability to return to sleep.

3 nights per week for 3 months

In insomnia disorder, how frequent is the sleep difficulty?

Sleep-onset insomnia

involves difficulty initiating sleep at bedtime

Sleep maintenance insomnia

involves frequent or prolonged awakenings throughout the night.

Late insomnia

early-morning awakening with an inability to return to sleep

Nonrestorative sleep

a complaint of poor sleep quality that does not leave the individual rested upon awakening despite adequate duration

Hypersomnolence Disorder

Self-reported excessive sleepiness (hypersomnolence)

despite a main sleep period lasting at least 7 hours, with at

least one of the folowing symptoms:

1. Recurrent periods of sleep or lapses into sleep within the

same day.

2. A prolonged main sleep episode of more than 9 hours per

day that is nonrestorative (i.e., unrefreshing).

3. Difficulty being fuly awake after abrupt awakening

Narcolepsy

Recurrent periods of an irrepressible need to sleep, lapsing into sleep, or napping occurring within the same day. These must have been occurring at least three times per week over the past 3 months.

Cataplexy

sudden loss of muscle tone while awake

Hypocretin

• Hypocretin (also called orexin) is a neuropeptide produced in the hypothalamus.

• It helps regulate wakefulness, arousal, and appetite.

• It plays a key role in preventing sudden transitions into REM sleep

Obstructive Sleep Apnea Hypopnea

is the most common breathing-related sleep disorder. It is characterized by repeated episodes of upper (pharyngeal) airway obstruction (apneas and hypopneas) during sleep. Each apnea or hypopnea represents a reduction in breathing of at least 10 seconds in duration in adults or two missed breaths in children and is typically associated with drops in oxygen saturation of ≥ 3% and/or an electroencephalographic arousal.

Apnea

refers to the total absence of airflow

hypopnea

refers to a reduction in airflow

polysomnogram

or sleep testing performed outside of the sleep center, referred to as out of center sleep testing [OCST]

Central Sleep Apnea

Brain fails to send proper signals to muscles that control breathing

Sleep-Related Hypoventilation

Shallow breathing during sleep → low oxygen, high CO₂.

Circadian Rhythm Sleep-Wake Disorders

A persistent or recurrent pattern of sleep disruption that is

primarily due to an alteration of the circadian system or to a

misalignment between the endogenous circadian rhythm and

the sleep-wake schedule required by an individual’s physical

environment or social or professional schedule.

Parasomnias

are disorders characterized by abnormal behavioral, experiential, or physiological events occurring in association with sleep, specific sleep stages, or sleep-wake transitions

Non–Rapid Eye Movement Sleep Arousal Disorders

Recurrent episodes of incomplete awakening from sleep,

usually occurring during the first third of the major sleep

episode, accompanied by either one of the following:

1. Sleepwalking: Repeated episodes of rising from bed

during sleep and walking about. While sleepwalking, the

individual has a blank, staring face; is relatively

unresponsive to the efforts of others to communicate with

him or her; and can be awakened only with great difficulty.

2. Sleep terrors: Recurrent episodes of abrupt terror

arousals from sleep, usually beginning with a panicky

scream. There is intense fear and signs of autonomic

arousal, such as mydriasis, tachycardia, rapid breathing,

and sweating, during each episode. There is relative

unresponsiveness to efforts of others to comfort the

individual during the episodes.

sleepwalking

is repeated episodes of complex motor behavior initiated during sleep, including rising from bed and walking about

sleep terrors

is the repeated occurrence of precipitous awakenings from sleep, usually beginning with a panicky scream or cry

Nightmare Disorder

Repeated occurrences of extended, extremely dysphoric, and well-remembered dreams that usually involve efforts to avoid threats to survival, security, or physical integrity and that generally occur during the second half of the major sleep episode

Rapid Eye Movement (REM) Sleep Behavior Disorder

• Acting out dreams due to lack of normal REM atonia (paralysis).

• May involve shouting, punching, or jumping during sleep.

• More common in older males and linked to neurodegenerative diseases (e.g., Parkinson’s).

Restless Legs Syndrome

An urge to move the legs, usually accompanied by or in

response to uncomfortable and unpleasant sensations in the

legs, characterized by all of the following:

1. The urge to move the legs begins or worsens during

periods of rest or inactivity.

2. The urge to move the legs is partially or totally relieved by

movement.

3. The urge to move the legs is worse in the evening or at

night than during the day, or occurs only in the evening or

at night.