The detrimental effects of sleep disturbances on health and wellbeing are well-established but not fully understood. The allostatic load model has been suggested as a framework for understanding the adverse effects of sleep disturbances. We conducted a systematic review and meta-analysis to examine the associations of sleep disturbance and sleep duration with allostatic load. PubMed, PsycINFO, Embase, and Web of Science were searched for records relating to sleep and allostatic load published from 1993 to January 14th, 2022. Two independent raters screened 395 titles and abstracts and 51 full texts. Data were extracted from 18 studies that were assessed for methodological quality. Of these, 17 studies of 26,924 participants were included in the meta-analysis. Sleep disturbance was significantly associated with higher allostatic load (effect size correlation [ESr] = 0.09, p < 0.001), and the association was weaker in samples with a larger proportion of women. When compared to normal sleep, long sleep was significantly associated with higher allostatic load (ESr = 0.12, p = 0.003). Results indicated heterogeneity. No association was found for short sleep (ESr = 0.05, p = 0.069) or sleep duration (ESr = −0.06, p = 0.36). Future research should identify mechanisms and directionality in longitudinal studies.