Discussion
mood disorders, reduced depression, depressed, depressed mood, Lewy, depressive disorders
PATHOGENESIS, PARRY, PATHOPHYSIOLOGY
The aim of this study was to determine whether PMDD depressed mood could be improved using phase-advancing sleep and light intervention (SALI) to correct the phase delay in melatonin circadian rhythms (CR) we found in PMDD (Parry et al. Importantly, we designed the study arms to create identical sleep restriction durations (4 h), plus identical bright light exposures (60 min/day for 7 days), but at different times of day, to effect maximal CR realignment. Thus, the treatments varied only in the times of day when sleep restriction and light exposure were instituted, with PAI designed to advance 6-SMT timing vs. PDI. That mood benefits and 6-SMT phase-advanced timing were, indeed, significantly correlated in the PAI vs. PDI study arms confirmed that hypothesis.We discuss implications of these findings in relation to previous literature below.Phase delay in CRs characterizes other depressive disorders. Lewy et al. (That the PAI, a phase-advancing SALI, reduced depression scores significantly more than the PDI, a phase-delaying SALI, confirms the hypothesis that phase-advancing CR is particularly effective in reducing PMDD depressed mood. Mood improvement after light treatment has been associated with a corrective phase shift of melatonin CRs in other depressive disorders: by Epperson et al. (The correlation of mood improvement magnitude with 6-SMT phase advance after PAI suggests the intervention engages a relevant pathogenesis: phase-delayed melatonin in the luteal menstrual cycle phase.These results suggest potential benefits for other reproductively related mood disorders when a circadian pathophysiology is identified. For example, in pregnancy, we showed plasma and urinary melatonin were phase advanced in depressed vs. healthy participants (Parry et al. The advantage of combining sleep and light interventions is that the sleep intervention hastens and potentiates mood benefits of light treatment, and light treatment maintains mood benefits of sleep intervention, which otherwise may be lost after a night of recovery sleep (Wirz-Justice These sleep and light interventions are safe, efficacious, rapid-acting, affordable, readily repeatable, well-tolerated with few side effects, non-pharmacological and non-hormonal home treatments that can be administered by paraprofessionals without office or clinic visits.Study limitations include a relatively small sample size, from only a single study site, and melatonin measured by 6-SMT rather than plasma. Further, as 37.5% of participants did not complete the full protocol, we confined conclusions about primary study outcomes to results of only participants who completed the full protocol. Although in our earlier study of wake therapy (Parry et al. 