Effects of Bright Light on Sleep Quality, Fatigue , and Mood Symptoms in Survivors With Gynecologic Cancer

The Effect of Bright Light Therapy on Sleep Quality, Cancer-Related Fatigue, and Emotional Symptoms in Gynecologic Cancer Survivors: A Randomized Controlled Trial

Objective: This study aimed to examine the efficacy of light therapy in improving sleep quality, reducing fatigue, and alleviating emotional symptoms among patients diagnosed with gynecologic cancer.

Methods: A randomized controlled trial was conducted at a medical center in northern Taiwan. Inclusion criteria included patients aged 18 years or older with a physician-confirmed diagnosis of gynecologic cancer and a score of ≥ 9 on the Chinese version of the Insomnia Severity Index (ISI-C). Eligible participants were randomly assigned to an experimental group or a control group (each with 47 subjects). At baseline (T0), all participants completed a demographic and treatment questionnaire, the ISI-C, the Taiwan version of the Brief Fatigue Inventory (BFI-T), and the Distress Thermometer (DT). The experimental group then underwent daily light therapy sessions via a circadian regulator for 30-40 minutes within 30 minutes of waking for four weeks. Meanwhile, the control group continued their usual routines during the same period. Follow-up assessments were conducted on days 7 (T1), 14 (T2), 21 (T3), and 28 (T4) post-intervention. Data was analyzed using SPSS 26.0, and generalized estimating equations (GEE) were employed to assess the effectiveness of light therapy.

Results: Generalized Estimating Equations (GEE) will be applied to examine group differences over time in sleep quality, fatigue, and emotional symptoms, in order to assess the effects of the intervention.

Conclusion: Light therapy is proposed as a potentially safe, low-risk, and cost-effective non-pharmacological intervention for improving sleep quality, reducing fatigue, and alleviating emotional distress in patients with gynecologic cancer following chemotherapy. This study is designed to evaluate the feasibility and potential effects of light therapy in this population, with the goal of informing future clinical applications.

Background and Rationale

Survivors of gynecologic cancers often experience persistent sleep disturbances, cancer-related fatigue, and emotional distress even after treatment has ended. These symptoms can significantly affect daily functioning, emotional well-being, and overall quality of life. Bright light therapy (BLT), a non-pharmacological intervention, has been shown in other populations to help regulate circadian rhythms and improve sleep and fatigue by suppressing melatonin levels. However, the application of BLT in gynecologic cancer survivors has not been well studied. This trial is designed to explore the potential of BLT in addressing these symptoms in this specific population.

Objectives

The primary objective is to evaluate the effects of a four-week bright light therapy intervention on sleep quality, fatigue, and emotional symptoms among gynecologic cancer survivors. It is hypothesized that participants receiving BLT will demonstrate improved outcomes in these domains compared to those receiving usual care.

Study Design

This is a randomized, controlled, single-blind trial with a parallel-group design. Eligible participants will be randomly assigned in a 1:1 ratio to either the intervention group (BLT) or the control group. Outcome assessors will remain blinded to group allocation throughout the study.

Intervention

Participants in the intervention group will receive bright light therapy using Re-Timer® light therapy glasses, which emit green-blue light at an intensity of 506 lux. Participants will be instructed to wear the glasses for 45 minutes each morning over four consecutive weeks. Sessions are self-administered at home between 7:00 AM and 9:00 AM, based on circadian rhythm guidance.

Control Condition

The control group will receive usual care and will not be provided with any light therapy. Participants in this group will be instructed to maintain their typical daily routines and avoid introducing new interventions that could impact sleep or mood during the study period.

Outcome Measures and Timepoints

Outcome data will be collected through an online questionnaire via the LINE messaging app at the following timepoints:

T1: Day 7 of intervention

T2: Day 14 of intervention

T3: Day 21 of intervention

T4: Day 28 of intervention

The following instruments will be used:

Insomnia Severity Index - Chinese version (ISI-C): to assess insomnia symptoms

Brief Fatigue Inventory - Taiwanese version (BFI-T): to assess cancer-related fatigue

Distress Thermometer (DT): to assess emotional distress

Inclusion Criteria:

1. Female participants aged 18 years or older.
2. Diagnosed with ovarian cancer, cervical cancer, fallopian tube cancer, or endometrial cancer, and have completed primary treatment (surgery, chemotherapy, or radiation) for more than 3 months, Currently in the treatment stage.
3. Insomnia Severity Index-Chinese Version (ISI-C) score ≥ 9, indicating clinical insomnia (Yang et al., 2009).
4. If currently using psychiatric medications, the dosage must have remained stable for at least 6 weeks prior to participation.
5. Able to speak Mandarin or Taiwanese fluently and read and write in Chinese.
6. Able to use a smartphone.
7. Conscious, capable of understanding the study procedures, willing to sign informed consent, and agree to participate.

Exclusion Criteria:

1. History of psychiatric hospitalization or severe psychiatric disorders within the past 6 months.
2. Eye diseases or ophthalmologic surgery within the past two weeks, conditions contraindicating light therapy, or use of photosensitizing drugs (e.g., cataracts).
3. Currently taking hypnotic medications.
4. Habitual smoking or alcohol use.
5. Working night shifts, rotating shifts, or frequent travel across multiple time zones.
6. Currently pregnant.