Biernacki MP, Jankowski KS, Kowalczuk K, Lewkowicz R, Dereń M. Aviat Space Environ Med 2012; 83:136–9. Background: Physiological effects of +G_z centrifugation are well known. Psychological functioning combined with +G_z centrifugation also appears to be important, but has not yet been sufficiently studied. This study was designed to evaluate whether mood (energetic arousal, tense arousal, and hedonic tone) is influenced by a centrifuge run with +G_z stress. Method: We examined subjects’ mood four times: 2 h prior to the centrifuge run, 2 min before and after centrifugation, and again 30 min afterwards. Energetic arousal (EA), tense arousal (TA), and hedonic tone (HT) assessments were conducted by the self-reported UWIST Mood Adjective Check List (UMACL). Results: Centrifugation explained 31.6% of EA and 56.9% of TA variance. EA level increased 2 min before centrifugation and remained so until the last measurement. TA was high 2 h prior to the centrifuge run, rose sharply 2 min before centrifugation, and lowered considerably after cessation of the run. The HT level was stable throughout all measurements. Conclusion: The centrifuge run with +G_z acceleration may evoke changes in arousal, but not in subjective enjoyment. Alterations in arousal levels triggered by centrifugation were positive, increasing energy and reducing tension.