Negative childhood experiences, such as abuse, neglect or loss of a parent, may bring a life-long burden of behavioural and pathophysiological problems. The risk for sleep disturbances and later emotional problems are widespread and prevalent. For many species the environment in which they develop is of a crucial importance for how they develop, the brain especially. Negative and stressful maternal regulatory input can induce long-term alterations in behavioural and neurobiological systems. In rats, maternal separation was combined with challenges to daily, uncontrollable mild stressors for 4 weeks as adults. Pups were separated daily from the dam during the postnatal days 2–14 for either180min (long maternal separation; LMS), 10min (brief maternal separation; BMS) or undisturbed (non-handled; NH). N=20 in all groups. As adults, they were further subdivided into 4 weeks of chronic mild stress (CMS) or control condition. Prior to CMS exposure, 8 LMS-CMS and 7 BMS-CMS animals were implanted with a subcutaneous telemetric device for EEG, EMG and peripheral body temperature measurements. LMS induces reduced body weight and lower brain activity (EEG power density) during wakefulness, slow-wave-sleep and REM sleep, an effect potentiated by CMS. LMS offspring showed also a vulnerability to later life challenges with reduced body weight gain, increased plasma corticosterone, reduced preference for sucrose (anhedonia-like measurement in rodents), lower body temperature, increased total sleep time, and REM sleep changes. BMS offspring seem more robust to handle chronic stressors as adults. Normal bodyweight gain, no change in plasma corticosterone, preference for sucrose or sleep, only transient changes of body temperature were found after CMS. Non-handled offspring seem also vulnerable to later life stress. An increased plasma corticosterone and less preference for sucrose were found. Long maternal separation results in lower brain activity and a weakness to handle later life challenges.