Any disorder of sleep or wakefulness per se; not a parasomnia.
Primary disorders of sleep or wakefulness characterized by insomnia or hypersomnia as the major presenting symptom. Dyssomnias are disorders of the amount, quality, or timing of sleep.
a disorder of getting to sleep or staying asleep or of excessive sleepiness
a disruption of the body's natural resting and waking patterns
A disorder of sleep, whether organic or functional.
Dyssomnias are a broad classification of sleeping disorder that make it difficult to get to sleep, or to stay sleeping.