Participants
DSM-5
DISORDER, MAY, CHRONIC INSOMNIA
Participants were recruited between February 23, 2021 and May 21, 2021, mostly through mailouts and online advertisement of a German health insurance company (Techniker Krankenkasse, TKK), but also through flyers in medical practices and online advertisement (social media). Eligibility requirements were: (a) a diagnosis of chronic insomnia disorder according to the DSM-5 classification criteria [