Bright light shows promise in improving sleep, depression, and quality of life in women with breast cancer during chemotherapy: findings of a pilot study

Abstract

Sleep and fatigue-associated symptoms are prominent during chemotherapy. The purpose of this pilot study was to examine bright light effects on sleep disruption, fatigue, daytime sleepiness, depression, and quality of life (QOL) in women with stage I-III breast cancer undergoing chemotherapy. In this 2-group randomized controlled trial (NCT02658708), participants were randomized to receive either blue-green light of 12,000 lux (experimental) or dim red light of 5 lux (control). Light therapy was self-administered using a light visor cap at home. Both groups received 30-minute daily light therapy for 21 consecutive days following the 2nd cycle of chemotherapy. Sleep quality, fatigue, daytime sleepiness, depression, and QOL were self-reported, and nocturnal sleep was monitored by ambulatory polysomnography before the initiation of chemotherapy (baseline) and following the light intervention (posttest). Relative change was assessed at posttest controlling for pretest scores. At posttest, the experimental group self-reported significantly shorter sleep latency than controls (10 vs. 20 min, p = .045) consistent with polysomnography findings (14 vs. 63 min). Polysomnography also revealed longer total sleep time (467 vs. 315 min) and higher sleep efficiency (74% vs. 58%) in experimental vs. controls. Participants receiving bright light experienced a 30% relative decrease in depression, while there was a 24% increase in the controls. The experimental group reported substantially fewer increases in symptom intensity than controls (33% vs. 166%). These findings suggest that bright light likely improved sleep quality and depression and mitigated worsening intensity of symptoms during the first three cycles of chemotherapy. However, features of bright light, e.g., treatment duration, frequency, and timing in relation to chemotherapy treatment require further investigation.

Keywords: Bright light; cancer; depression; fatigue; quality of life; sleep quality.

Conflict of interest statement

Disclosure statement.

The authors report no conflict of interest.

Figures

Figure 1.

Mean PHQ Depression Scores Over Two Assessments

Figure 2.

Mean Symptom Scores Over Two Assessments

Figure 3.

Mean Functional Scores Over Two Assessments

Figure 4.

Mean Sleep Onset Latency Over Two Assessments