Insomnia disorder.

Insomnia disorder (ID) causes both night-time and daytime symptoms. Night-time symptoms include subjective difficulties initiating and maintaining sleep and early morning awakenings, whereas fatigue, perceived impairments in cognitive functioning, and mood disturbances are common daytime symptoms. The prevalence of ID in adults is high (10-16%) and the condition represents a substantial burden for both patients and society. ID is also an independent risk factor for other mental disorders and physical diseases. Diagnosis relies on self-report, as a biomarker for the disorder has not yet been established. The aetiological and pathophysiological understanding of ID spans from epigenetic and genetic research to cognitive behavioural and psychophysiological approaches. Clinical guidelines recommend cognitive behavioural therapy for insomnia (CBT-I) as the first-line treatment. However, CBT-I still requires widespread implementation, with digital CBT-I offering a scalable solution to improve treatment accessibility. Most available hypnotic agents are recommended solely for short-term use, owing to their limited efficacy and potential adverse effects. Given the considerable proportion of patients who respond insufficiently to medications and the need for further research on CBT-I, the development of novel interventions and the refinement of existing treatments is urgently required.