Close relationships have been reported between sleep alterations and suicidal behaviors, nevertheless few studies used objective measures of sleep. Such objective markers would be interesting in clinical practice to better screen and prevent suicide. We conducted a systematic review and meta-analysis of published studies examining the relationship between sleep markers and suicidal behaviors using PubMed, Cochrane Library, and Web of Science databases. Actigraphy, polysomnography, and nocturnal EEG were considered. The qualitative analysis retained 15 original studies, including 1179 participants (939 with a psychiatric disorder), and 11 studies were included for the meta-analysis. Current suicidal behaviors were associated with a decreased total sleep time (TST) (SMD = −0.35, [95% CI: −0.66 to −0.04], p = 0.026, I² = 39.8%). The evaluation of possible moderators shows that age, gender, and depression scores had no effects on the random effect model. No significant differences were observed regarding sleep efficiency, REM latency, or percentage of REM sleep. In conclusion, among candidate objective markers, decreased total sleep time seems associated with suicidal behaviors and could be easily used to assess suicide risk. Alterations of regular sleep duration should invite healthcare professionals to screen the cause and propose sleep interventions to prevent suicide.