Objective: This study aimed to investigate prescription patterns in patients with insomnia who still met the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria despite having already been taking hypnotics, and to determine which drug(s) and what combination therapies were preferred. Methods: Sixty-three patients were enrolled in this study. Patients were selected from participants registered at six university hospitals for a prospective study to evaluate the efficacy of melatonin (Circadin).Results: The prescribed hypnotics were clonazepam (n=33), trazodone (n=23), zolpidem (n=22), quetiapine (n=14), mirtazapine (n=12), lorazepam (n=10), alprazolam (n=7), triazolam (n=5), doxepin (n=5), diazepam (n=3), etizolam (n=2), and flunitrazepam (n=1). There were five types of monotherapies (benzodiazepine, zolpidem, trazodone, mirtazapine, and doxepin) and 18 types of combination therapies. The total number of hypnotics used ranged from one to six. The frequency of benzodiazepine use was quite high, at 51/63. Conclusion: This study showed that insomnia can be treated in a wide variety of ways. In particular, 63% of the insomnia treatments in this study used combination therapy. This means that the gap between evidence-based pharmacotherapy and pharmacotherapy used in clinical practice is substantial. This also means that insomnia is still not fully understood and is a heterogeneous condition. In the future, more studies are needed to deepen our understanding of the pathophysiology of insomnia.