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. Method Data were collected from 106 patients with major depression consecutively admitted to the psychiatry clinic of Yüzüncü YIl University School of Medicine and 200 were volunteers recruited from community sample who were enrolled at the university. The SHI, Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI) and Epworth Sleepiness Scale (ESS) were administered to the subjects. Factor structure of the SHI was evaluated with explanatory and multi-sample confirmatory factor analyses. Pearson product-moment correlation coefficients of the SHI with the PSQI, ISI and ESS were computed. Item analyses, internal consistency coefficients and intra-class correlations between two repeated applications in both patient and healthy subjects were calculated. Results The SHI revealed a unidimensional factor structure. Significant strong partial associations of the SHI with depression, insomnia and poor sleep quality and a modest partial association with sleepiness were detected. Cronbach's alphas for the SHI in community sample and patients with major depression were 0.70 and 0.71, respectively. Additionally, we found acceptable three-week temporal reliability in terms of intra-correlation coefficients of r = 0.62, p < 0.01 for the community sample and of r = 0.67, p < 0.01 among patients with major depression. Conclusion The SHI revealed adequate validity and reliability to be used by researchers in Turkish sample. Current results were discussed in light of previous findings and theoretical considerations.