Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.2010.431.436ZamanianZ. KakooeiH. AyattollahiS.M.T. DehghaniM. 92010139The aim of this study are to assess, in a hospital setting, the effects of Bright Light (BL) on the rhythms in body temperature, plasma melatonin, plasma cortisol and subjective alertness during shift work. In our experimental design, 34 healthy shift work nurses from a university hospital were exposed to bright light (4500 lux) during two break times (21:15 to 22; 00 and 3:15 to 4:00) for four consecutive weeks. In this survey, the subjects were studied under 24 h of realistic conditions during which their plasma cortisol and plasma melatonin was measured at 3 h intervals. In addition, their body temperatures were measured during and after night shift work. Subjective alertness and fatigue were evaluated with the Karolinska Sleepiness Scale (KSS) and Visual Analog Scale (VOI). It was found that bright light administration significantly suppressed nighttime melatonin levels during night shift, most strongly at 2:00 a.m. A one-way ANOVA, with repeated measurement design, revealed that Bright Light (BL) tended to increase cortisol levels and body temperature and improved alertness significantly during night shift. These results demonstrate that photic stimulation in a hospital setting can have a powerful influence on the adjustment of the circadian system.]]>Allan, J.S. and C.A. Czeisler,199479508512Badia, P., B. Myers, M. Boecker, J. Culpepper and J.R. Harsh,199150583588Baehr, E.K., W. Revelle and C.I. Eastman,20009117127Bonnet, M.H.,19904261274Brown-DeGagne, A.M. and G.A. Eskes,1998945152Cajochen, C., S.B.S. Khalsa, J.K. Wyatt, C.A. Czeisler and D.J. Dijk,1999277640649Czeisler, C.A.,1995183254290Dawson, D., N. Encel and K. Lushington,1995181121Dijk, D.J., J.F. Duffy and C.A. Czeisler,19921112117Dinges, D.F., F. Pack, K. Williams, K.A. Gillen and J.W. Powell et al.,199720267277Duffy, J.F., R.F. Kronauer and C.A. Czeisler,1996495289297Eastman, C.I., L. Liu and L.F. Fogg,199518399407Estryn-Behar, M., M. Kaminski, F. Peigne, N. Bonnet and E. Vaichere et al.,1990472028Foret, J., A. Daurat and G. Tirilly,19983115120Goldberg, D. and V.C. Hillier,19799139145Hawley, M.P.,199218211216Hunt, T. and P. Sassone-Corsi,2007129461464Jaffe, M.P., M.H. Smolensky and C.C. Wun,199689305312Kenneth, P., J., Wright, J.T. Hull and C.A. Czeisler,2002283R1370R1377Khalsa, S.B.S., E.J. Megan, C. Christian and C.A. Czeisler,2003549945952Lewy, A. and D. Newsome,19835611031107Lewy, A., T. Wehr and F. Goodwin,198021012671269Lewy, A., S. Ahmed and R.L. Sack,199573131134Lewy, A., V.K. Bauer, S. Ahmed, K.H. Thomas and N.L. Cutler et al.,1998157183Nemchin, A.A., M.J. Whitehouse, M. Menneken, T. Geisler, R.T. Pidgeon and S.A. Wilde,20084549295Saiepour, N., K. Mohammad, R. Abhari, H. Zeraati and A.A. Noorbala,200811809812Scott, A.J.,19947207233Shanahan, T.L., J.M. Zeitzer and C.A. Czeisler,199712556567Stevens, R.G., D.E. Blask, G.C. Brainard, J. Hansen and S.W. Lockley et al.,200711513571362Van Cauter, E., J. Sturis, M.M. Byrne, J.D. Blackman and R. Leproult et al.,1994266E953E963Vujovic, N., A.J. Davidson and M. Menaker,2008295R355R360Wever, R., J. Polasek and C. Wildgruber,19833968587Wright, K.P.J, P. Badia, B.L. Myers and S.C. Plenzler,199762635Wright, K.P.J., P. Badia, B.L. Myers, S.C. Plenzler and M. Hakel,19977477884Wyatt, J.K., A.R. de Cecco, C.A. Czeisler and D.J. Dijk,1999277R1152R1163Youngstedt, S.D., D.F. Kripke and J.A. Elliott,2002282R259R266Ardekani, Z.Z., H. Kakooei, S.M.T. Ayattollahi, A. Choobineh and G.N. Seraji,20081116051609