Describe the features of the major types of dyssomnias.

Dyssomnias encompass a range of sleep disorders characterised by difficulties in obtaining adequate sleep, including trouble falling asleep, maintaining sleep, or achieving restorative rest.

Primary Insomnia

Involves difficulty initiating or maintaining sleep unrelated to other conditions. Key features include "unrealistic expectations about sleep" and the perception that sleep loss creates greater disruption than is typical for the individual.

Primary Hypersomnia

Represents excessive daytime sleeping unconnected to other disorders. Individuals report sleeping throughout the day while also being able to "sleep throughout the night," indicating a disrupted sleep-wake regulatory system.

Narcolepsy

Features uncontrollable daytime sleepiness often triggered by emotions. Characteristics include sleep paralysis, hypnagogic hallucinations, cataplexy (sudden muscle weakness triggered by emotion), and persistent daytime drowsiness requiring medical treatment.

Breathing-Related Sleep Disorder

Involves restricted airflow or breathing interruptions during sleep. Features include snoring, "morning headache, occurrence of sweat during sleep, frequent awake" episodes, and minimal awareness of apnea occurrences by the sufferer.

Circadian Rhythm Sleep Disorder

Results from the brain's inability to synchronise internal timing with day-night cycles. Manifestations include jet lag from time zone changes, sleep disruptions from shift work, and various phase disorders affecting the timing of the sleep-wake cycle.