The goal of this clinical trial is to learn about insomnia treatment among primary care patients with chronic insomnia. The main question it aims to answer is: • Does Sleep School (a therapy for insomnia) work well to decrease harm of insomnia? Participants will attend a group therapy intervention once a week for six weeks. Researchers will compare Sleep School to treatment as usual (short counselling by an educated nurse) to see if the Sleep School works better than treatment as usual in decreasing the harm of insomnia.