Mayonaka no Orphe

30 year-old Kazushi is an insomniac who suffers from Post-Traumatic Stress Disorder. Plagued with terrible nightmares that neither medication nor therapy have been able to alleviate, the perpetually exhausted man has become terrified of sleep. When his coworker Wabuka learns of his condition after he passes out at work one day, the gentle man holds Kazushi's hand and uses his deep, melodious voice to lull him into a peaceful, nightmare-free slumber. The next morning, Wabuka suggests that they live together so that he can help Kazushi sleep at night, and the two men begin an unusual form of cohabitation. Adult male work colleagues sleeping belly-to-belly as if they were lovers is undoubtedly strange; but the longer it goes on, Wabuka finds Kazushi growing more and more precious to him...

(Source: Anime-Planet)