Perceived ethnic discrimination is central to the experiences of Latino young adults, yet we know little about the ways in which and the conditions under which ethnic discrimination relates to Latino young adults’ sleep patterns. Using a sample of 246 Mexican-origin young adults (M age = 21.11, SD = 1.54; 50 % female), the current study investigated the longitudinal links between perceived ethnic discrimination and both sleep duration and night-to-night variability in duration, while also examining the moderating roles of Anglo and Mexican orientations in the associations. The results revealed that perceived discrimination predicted greater sleep variability, and this link was not moderated by cultural orientations. The relation between perceived discrimination and hours of sleep, however, was moderated by Anglo and Mexican orientations. Individuals with high Anglo and Mexican orientations (bicultural) and those with only high Mexican orientations (enculturated), showed no association between discrimination and hours of sleep. Individuals with low Anglo and Mexican orientations (marginalized) displayed a positive association, whereas those with high Anglo and low Mexican orientations (acculturated) displayed a negative association. The results suggest that discrimination has long term effects on sleep variability of Mexican-origin young adults, regardless of cultural orientations; however, for sleep duration, bicultural and enculturated orientations are protective.