Critically-timed sleep + light interventions for improving mood in pregnancy vs. postpartum depression.

A recent study tested the hypothesis that combined wake + light therapy improves mood in pregnant vs. postpartum depressed participants (DP) by differentially altering melatonin and sleep timing.

Initially, the study randomized 89 women, 37 pregnant (21 normal controls-NC; 16 DP) and 52 postpartum (27 NCs; 25 DP), to a trial of a phase-delay intervention (PDI): 1-night of early-night wake therapy (sleep 3-7 am) + 6-weeks of evening bright white light (Litebook Advantage) for 60 min starting 90 min before bedtime, vs. a Phase-advance intervention (PAI): 1-night of late-night wake therapy (sleep 9 pm-1 am) + 6-weeks of morning bright white light for 60 min within 30 min of wake time. Blinded clinicians then assessed mood weekly by structured interview, and participants completed subjective ratings, a Morningness-Eveningness questionnaire, actigraphy, and collected two overnight urine samples for 6-sulphatoxy melatonin (6-SMT).

The study observed-

• In pregnant DP, mood improved more after the PDI vs. PAI.
• In postpartum DP, mood improved more after the PAI vs. PDI.
• After wake therapy, two weeks of light treatment showed similar efficacy as six weeks. 
• In postpartum DP, PAI phase-advanced 6-SMT offset and acrophase, which linked positively with mood improvement magnitude.

This study shows that the mood improves more after two weeks of the PDI in pregnant DP but more after two weeks of PAI in postpartum DP, in which improvement magnitude correlates with 6-SMT phase-advance. Thus, critically-timed Sleep + Light Interventions deliver safe, efficacious, rapid-acting, well-tolerated, at-home, non-pharmaceutical therapies for peripartum DP.

Barbara L. Parry, Charles J. Meliska, Diane L. Sorenson, L. Fernando Martinez, Ana M. Lopez, Sharron E. Dawes, Jeffrey A. Elliott, Richard L. Hauger. Critically-timed sleep+light interventions differentially improve mood in pregnancy vs. postpartum depression by shifting melatonin rhythms. Journal of Affective Disorders. 2023;324: 250-258. https://doi.org/10.1016/j.jad.2022.12.079.