Sleep's contribution to affective regulation is insufficiently understood. Previous human research has focused on memorizing or rating affective pictures and less on physiological affective responsivity. This may result in overlapping definitions of affective and declarative memories, and inconsistent deductions for how rapid eye movement sleep (REMS) and slow-wave sleep (SWS) are involved. Literature associates REMS theta (4-8Hz) activity with emotional memory processing, but its contribution to social stress habituation is unknown.Applying selective sleep stage suppression and oscillatory analyses, we investigated how sleep modulated affective adaptation towards social stress and retention of neutral declarative memories. Native Finnish participants (N=29, age M=25.8y) were allocated to REMS or SWS suppression conditions. We measured physiological (skin conductance response, SCR) and subjective stress response and declarative memory retrieval three times: before laboratory night, the next morning, and after three days. Linear mixed models were applied to test the effects of condition and sleep parameters on emotional responsivity and memory retrieval.Greater overnight increase in SCR towards the social stressor emerged after suppressed SWS (intact REMS) relative to suppressed REMS (20.1% vs. 6.1%, p=.016). The overnight SCR increase was positively associated with accumulated REMS theta energy irrespective of the condition (r=.601, p=.002). Subjectively rated affective response and declarative memory recall were comparable between the conditions.The contributions of REMS and SWS to habituation of social stress are distinct. REMS theta activity proposedly facilitates the consolidation of autonomic affective responses. Declarative memory consolidation may not have greater dependence on intact SWS relative to intact REMS.Significance statement Disrupted sleep is a common problem with negative effects on affective regulation. While research indicates that rapid eye movement sleep has a central role in off-line affective processing, the mechanisms are not well defined. We used selective sleep stage suppression to investigate how disrupted sleep and stage-specific neural activity modulated the affective responsivity towards a self-conscious stressor inducing shame. We show that theta band oscillatory activity during rapid eye movement sleep is especially important for preserving the physiological stress response overnight. Understanding sleep-driven affective regulation facilitates development of applications aiming at improving mental wellbeing.