RÉSUMÉ
Objectives@#：This study aimed to examine the mediating effect of sleep quality and interpretation bias for ambiguity in the relationship between hopelessness and suicidal ideation in psychiatric patients. @*Methods@#：A total of 231 psychiatric outpatients and inpatients completed the Beck Hopelessness Scale, Pittsburgh Sleep Quality Index, Ambiguous/Unambiguous Situations Diary-Extended Version, and Ultra-Short Suicidal Ideation Scale. Data analysis was conducted using regression analyses and bootstrap sampling. @*Results@#：The results of this study showed that hopelessness had a direct effect on suicidal ideation, and that sleep quality and interpretation bias for ambiguity mediated the association between hopelessness and suicidal ideation. Moreover, there was a significant double mediating effect of sleep quality and interpretation bias for am-biguity on the relationship between hopelessness and suicidal ideation. @*Conclusions@#：These results suggest that it is important to consider both sleep quality and interpretation bias for ambiguity to prevent hopelessness from leading to suicidal idea. These results suggest that considering both sleep quality and interpretation bias for ambiguity may be important in preventing hopelessness from leading to suicidal ideation.