Chronodisruption can be involved in development of several diseases and it is necessary to elucidate possible causal physiological, behavioural and psychosocial mechanisms underlying these adverse effects. In our model of chronic phase shifts in a lightning regimen disturbed rhythms of cardiovascular parameters and activity were found in rats. In the present study, we manipulated either the lightning schedule or both lightning and feeding regimens to analyse an ability of desynchronized rats to cope with emotional stressors. Adult male Wistar rats (n=12) were implanted into the abdominal aorta with radio-telemetric transmitter TA11PA-C40 (DSI, Minnesota, USA) to continuously monitor heart rate (HR) and blood pressure (BP). A mixture of ketamine (75mg kg-1) and xylazine (10mg kg-1, i.p.) was used as anaesthesia. Following synchronisation to the LD regimen of 12:12h, one half of the rats were exposed to phase delay shifted (PDS) schedule (by 8 hours longer dark phase every second day over 5 weeks). In both groups, diet (Fresubin-isocaloric liquid drink, Fresenius Kabi, Germany) was provided only during the passive phase of the day. Cardiovascular response to a novelty (open-field test) was measured before (0w) and 5 weeks (5w) after the treatment. In addition, two groups of non-implanted rats were simultaneously housed under either control LD (n=8) or PDS (n=8) regimens with standard diet ad libitum. After 5 weeks, their behaviour was quantified in the open-field test, the black-white box and the elevated plus maze using video-tracking software Any-maze (Stoelting Co.). Cardiovascular response was analysed as an increase of HR and systolic BP over the basal levels during the 20-minute test. An area under the curve was calculated (means ± S.E. are given) and compared between 0w and 5w within each treatment by paired t-tests. Rats on the control LD regimen with diet in antiphase decreased their cardiovascular response between 0w and 5w (HR: 118694±15596 vs. 48427±18632; BP: 23045±474 vs. 17857±705) while no changes were found in rats on PDS regime with diet in antiphase (HR: 103633±8198 vs. 71717±23414; BP: 22438±2996 vs. 19506±4198). Behaviour of non-implanted rats on control LD and PDS regimens was analysed by independent t-tests. As compared to controls, PDS rats displayed increased locomotion and rearing in both the open-field and black-white box tests. They spent more time in the white compartment of the black-white box and showed increased risk assessment behaviour and decreased grooming in the elevated plus maze. In conclusion, disturbances of two strong Zeitgebers influenced the pattern of stress induced changes in HR and BP as well as spontaneous motor activity and exploration in rats. Results indicate that weakened circadian organization may alter an ability to cope with stressful events.