Objective: Sleep is one of the most significant of human behaviors, occupying roughly one third of human life. Sleep is a process the brain requires for proper functioning. Sleep hygiene can be described as practices to ease sleep and to avoid factors which decrease sleep quality. Inadequate sleep hygiene generally results in disturbance of daily life activities due to inability to sustain sleep quality and daytime wakefulness. Therefore, the importance of development and utilization of measures of sleep hygiene increases. The aim of the study was to assess psychometric properties of the Sleep Hygiene Index (SHI) in clinical and non-clinical Turkish samples.