The effect of bright light therapy on sleep in pregnant women with major depressive disorder– a randomized controlled trial

Purpose: 

Bright light therapy (BLT) is a potential treatment for depression during pregnancy, which may also improve sleep. We investigated whether BLT has an effect on self-reported and actigraphy-estimated sleep in pregnant women diagnosed with depressive disorder. 

Method: 

Sixty-seven pregnant women with a DSM-5 diagnosis of depressive disorder during pregnancy were randomly allocated to treatment with BLT (9,000 lx, 5,000 K) or dim red light therapy (DRLT, 100 lx, 2,700 K), which is considered placebo. For six weeks, both groups were treated daily at home for 30 min upon awakening. Follow-up took place at various time points. We collected data on sleep with the Pittsburgh Sleep Quality Index and with actigraphy wearables. 

Results:

We found no statistically significant differences in treatment groups across any of the sleep parameters measured, namely sleep efficiency, duration, onset latency, fragmentation, and total sleep health as measured by self-report and actigraphy. Moreover, we observed no overall improvements in sleep during the treatment period. 

Conclusions: 

The results suggest that any potential therapeutic effects of BLT might have on sleep are too small for the current study to detect.