Light treatment in depressive illness. Polysomnographic, psychometric and neuroendocrinological findings

Abstract

Objective and subjective quality of sleep and awakening as well as circadian rhythms in cortisol, temperature and well-being were investigated in 10 female hospitalized depressed patients diagnosed as major depressive disorders according to RDC criteria before (baseline), during (intervention) and after (recovery) treatment with biologically active or bright light (BL) and were compared with the findings in 10 normals. Polysomnographic evaluation demonstrated in depressed patients an increased sleep latency, decreased total sleep time, attenuated S4 and augmented REM sleep, as well as a shortened REM latency and a statistically significant increased average REM length as compared with normals. BL tended to shorten sleep onset, decrease number of awakenings, increase REM latency and significantly attenuated the average REM length. Subjective sleep quality tended to improve as did the subjective awakening quality after the recovery night. There was, however, a statistically significant improvement of the objectively evaluated quality of awakening and early morning behavior characterized by an improved attention, reaction time and performance in the reaction time task, while concentration and psychomotor activity tended to improve as as well. BL effects were also seen in hormonal secretion patterns: circadian cortisol secretion maxima occurred earlier in depressed patients than in normals before and after BL treatment, while during BL intervention this difference disappeared. Circadian temperature rhythms did not exhibit any significant findings with the exception of an earlier occurring minimum in depressed patients than in normals after treatment. Finally, subjective well-being as rated by means of an analogue scale was significantly worse in depressed patients than normals before but not during and after light treatment. The findings are discussed.