Table 1 Inclusion and exclusion criteria

18–85 years

Insomnia disorder conform DSM-5

Score of ≥ 10 on the Insomnia Severity Index

Long term medical condition

Study-related exclusion criteria:

Habitual night shifts

Untreated sleep-related breathing disorder

Wish to continue over-the-counter sleep aids

Off-label amitriptyline for insomnia in past year

Epilepsy, dementia, history of delirium

Pregnancy, lactation or pregnancy wish

Terminal illness

Ocular hypertension/glaucoma

Severe psychiatric disorder

Substance abuse/addiction (benzodiazepine excluded)

Potential drug-drug interactions for amitriptyline:

Use of psychopharmaceuticals (other than benzodiazepine) or antimyotics

Contra-indications for amitriptyline:

Allergy for amitriptyline

Cardiac disorders

Severe renal insufficiency or liver dysfunction