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

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

• Female participants aged 18 years or older.
• 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.
• Insomnia Severity Index-Chinese Version (ISI-C) score ≥ 9, indicating clinical insomnia (Yang et al., 2009).
• If currently using psychiatric medications, the dosage must have remained stable for at least 6 weeks prior to participation.
• Able to speak Mandarin or Taiwanese fluently and read and write in Chinese.
• Able to use a smartphone.
• Conscious, capable of understanding the study procedures, willing to sign informed consent, and agree to participate.

Exclusion criteria

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