INTRODUCTION: Human attachment is known to be closely associated with psychophysiological phenomenon. However, there have not been enough researches on the relationship of the attachment with sleep, especially with insomnia. The objective of the present study was to investigate the relationship between adult attachment styles and insomnia in community-dwelling population. METHODS: One hundred seventy seven community-dwelling adults (74 males and 103 females ;mean age 41.23+/-8.44) participated in the current study. To assess the attachment styles (secure, dismissing, preoccupied and fearful), self-reporting Relationship Style Questionnaires (RSQ) were completed by the participants. Presence, type, frequency and duration of insomnia in the last month were also investigated. RESULTS: Compared to subjects without insomnia, subjects with insomnia had higher fearful attachment scores (t =2.87, p=0.005). Higher fearful attachment score were found in all subtypes of insomnia (sleep-onset insomnia, t =2.33, p=0.021;maintenance insomnia, t=2.92, p=0.004;terminal insomnia, t=2.89, p=0.004). Subjects with frequent (>or =3 per week) insomnia had higher fearful attachment scores than subjects with infrequent (or =6 months) had higher preoccupied attachment scores relative to subjects with transient insomnia (<6 months), (t=2.57, p=0.012). CONCLUSION: In the current study, attachment styles were different depending on the characteristics of insomnia. The fearful attachment was associated with the presence of insomnia, while the preoccupied attachment was associated with the chronicity of insomnia. These findings suggest that there may be some relationship between the adult attachment styles and the clinical features of insomnia.