F50-F59: Behavioural syndromes associated with physiological disturbances and physical factors

F51: Nonorganic sleep disorders

Nonorganic sleep disorders, as classified under ICD-10 code F51, represent a group of conditions related to disruptions in sleep patterns, but not caused by any identifiable physical or mental disorder. Typically, these conditions arise from abnormal sleep-wake schedules or the presence of environmental stimuli. Common types of nonorganic sleep disorders include insomnia, sleepwalking, sleep terrors, and nightmare disorder. Common symptoms of these disorders include difficulty falling asleep, persistent nightmares, sleepwalking, and often waking up feeling unrefreshed. The disturbances in sleep can lead to impairment in social, occupational, or other crucial areas of functioning, causing significant distress or challenges for the affected individuals. The exact cause of these disorders may vary widely, depending on the specific type of sleep disorder. It's important to note that these disorders are considered "nonorganic," meaning they aren't directly caused by a physical health problem, but rather from an external source or behavioral habit.