The Effect of Bright Light Therapy on Sleep Quality, Cancer-Related Fatigue, and Emotional Symptoms in Gynecologic Cancer Survivors: A Randomized Controlled Trial
Phase: NA
Conditions: Gynecologic Cancer Survivors, Sleep Quality, Fatigue, Mood Symptoms
Sponsor: Chang Gung Memorial Hospital

Official Title：Efficacy of Light Therapy in Improving Sleep Quality, Fatigue, and 
Emotional Symptoms in Patients with Gynecologic Cancer 
NCT 編號：Pending 
Document Date：2024.12.15 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Efficacy of Light Therapy in Improving Sleep Quality, Fatigue, and Emotional 
Symptoms in Patients with Gynecologic Cancer 
Abstract 
Objective: This study aims 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. Participants were eligible if they were aged 18 years or older, had a physician-
confirmed diagnosis of gynecologic cancer, and reported an Insomnia Severity Index – 
Chinese version (ISI-C) score of ≥ 9. Eligible participants were randomly assigned to 
either an experimental group or a control group (n = 47 per group). At baseline (T0), 
participants completed a demographic questionnaire, ISI-C, the Brief Fatigue Inventory 
– Taiwanese version (BFI-T), and the Distress Thermometer (DT). The experimental 
group received daily morning light therapy for 30–40 minutes over four weeks using a 
circadian-regulating light device. The control group continued their usual routines 
during the same period. Follow-up assessments were scheduled at day 7 (T1), day 14 
(T2), day 21 (T3), and day 28 (T4). Data will be analyzed using generalized estimating 
equations (GEE) to evaluate the effects of the intervention on sleep quality, fatigue, and 
emotional symptoms. 
Keywords: light therapy, gynecologic cancer, chemotherapy, sleep quality, fatigue, 
emotional symptoms. 
 
 

Research Motivation and Significance 
Gynecologic malignancies, including cervical, endometrial, and ovarian cancers, 
account for approximately 14.4% of all female cancers in Taiwan. Chemotherapy 
remains a mainstay treatment but is often accompanied by adverse symptoms such as 
fatigue, emotional distress, and sleep disturbances—each significantly impairing 
quality of life and possibly prognosis.Approximately 9% to 45% of cancer patients 
experience moderate-to-severe fatigue, and over half of women with gynecologic 
cancer report persistent sleep disturbances, often worsened by psychological symptoms. 
While pharmacological treatments exist, they frequently cause undesirable side effects. 
Consequently, interest has grown in non-pharmacological interventions like light 
therapy, which modulates circadian rhythms through suppression of melatonin and 
enhancement of serotonin.Re-Timer® light therapy glasses (500 nm wavelength, 500 
lux) offer a safe, user-friendly, FDA-cleared home-based solution. By stimulating 
intrinsically photosensitive retinal ganglion cells (ipRGCs) and acting on the 
suprachiasmatic nucleus (SCN), Re-Timer® stabilizes circadian rhythms, thereby 
potentially improving sleep, fatigue, and mood regulation.Despite growing evidence, 
limited studies have evaluated the efficacy of light therapy in gynecologic cancer 
survivors. This study aims to assess the therapeutic effects of bright light therapy using 
Re-Timer® in alleviating chemotherapy-related sleep disturbances, fatigue, and 
emotional distress, and to provide evidence for clinical implementation of non-
pharmacological symptom management strategies in this population.Methods 
Research Design 
This study utilized a randomized controlled trial (RCT) design and was 
implemented at the gynecologic outpatient department of a tertiary medical center in 
northern Taiwan. 
Research Setting and Participants 

This study was conducted at a tertiary medical center in northern Taiwan between May 
13 and December 12, 2024.Eligible participants were individuals aged 18 years or older 
with a physician-confirmed diagnosis of gynecologic cancer and an Insomnia Severity 
Index-Chinese version (ISI-C) score of 9 or above. All participants provided written 
informed consent prior to enrollment.Exclusion criteria included the presence of visual 
impairment or photosensitivity that could interfere with the use of light therapy devices, 
a current diagnosis of psychiatric disorders or cognitive impairment, and any physical 
limitations that would hinder adherence to the intervention protocol or data collection 
due to disease severity.Sample Size Calculation and Randomization 
Sample size was calculated using G*Power 3.1, assuming a medium effect size (f = 
0.25), a significance level of α = 0.05, and a statistical power of 0.80 for a two-group 
comparison. The estimated minimum sample size was 78 participants. Allowing for an 
anticipated attrition rate of 20%, the target enrollment was increased to 94 participants. 
Participants were randomly assigned to either the experimental or control group in a 
1:1 ratio using the random number generator function in Microsoft Excel (Microsoft 
Corporation, Redmond, WA, USA). Each group ultimately included 47 participants. 
Data Collection and Ethical Considerations 
Ethical Approval and Informed Consent：The study protocol was approved by the 
Institutional Review Board (IRB) of the participating medical center (CGH-IRB No. 
202400345A3C601). Participant recruitment was conducted in the gynecologic 
outpatient department. Before enrollment, all participants received a thorough 
explanation of the study's objectives, procedures, potential risks, and anticipated 
benefits. They were assured that their personal data would be anonymized, securely 
stored, and used solely for academic research purposes. Participants were informed of 
their right to withdraw from the study at any time without affecting their ongoing 
clinical care. Written informed consent was obtained from all participants. 

Baseline Assessment and Intervention ：Following consent, participants 
completed baseline assessments (T0), including a demographic and treatment 
questionnaire, the Insomnia Severity Index – Chinese version (ISI-C), the Taiwanese 
version of the Brief Fatigue Inventory (BFI-T), and the Distress Thermometer 
(DT).Participants randomized to the experimental group were instructed to wear the 
Re-Timer® circadian regulator glasses for 30–40 minutes each morning within 30 
minutes of waking, for four consecutive weeks. Participants recorded daily light therapy 
duration and sleep hours. If any discomfort occurred during the intervention, therapy 
was discontinued immediately, and support was provided by the research team.The 
control group was instructed to continue their regular daily routines without any light 
therapy intervention. 
Follow-up Assessments ：Outcome measures (ISI-C, BFI-T, and DT) were 
reassessed via an online questionnaire delivered through the LINE messaging app on 
Days 7 (T1), 14 (T2), 21 (T3), and 28 (T4) after the start of the intervention 
Measurement Instruments 
Demographic and Treatment-Related Variables： 
Data collected included participants’ age, body mass index (BMI), education level, 
marital status, religious affiliation, employment status, cancer type, cancer stage, use of 
sleep medications, and history of emotional distress. Treatment-related variables 
encompassed the current treatment modality, time since treatment completion, and 
general health status. 
Sleep Quality： 
Sleep quality was assessed using the Chinese version of the Insomnia Severity 
Index (ISI-C), which evaluates the severity and impact of insomnia symptoms over the 
past two weeks. The seven items cover: 
 

Difficulty initiating sleep 
Difficulty maintaining sleep 
Early morning awakening 
Satisfaction with current sleep pattern 
Interference with daily functioning 
Noticeable impairment in quality of life due to sleep problems 
Degree of worry or distress about sleep difficulties 
Each item is rated on a 5-point Likert scale (0–4), with total scores ranging from 
0 to 28; higher scores indicate more severe insomnia. The original ISI was developed 
by Morin et al. (1993), and the Chinese version was validated by Yang et al. (2009). 
The ISI-C demonstrates excellent internal consistency (Cronbach’s α = 0.91) and high 
concurrent validity with the Chinese version of the Pittsburgh Sleep Quality Index (r = 
0.88). A cutoff score of ≥9 yields a sensitivity of 91.8% and specificity of 91.2%. 
Fatigue： 
Fatigue severity was measured using the Taiwanese version of the Brief Fatigue 
Inventory (BFI-T), which was originally developed at the University of Texas MD 
Anderson Cancer Center (Mendoza et al., 1999). The BFI-T assesses fatigue 
experienced in the past 24 hours across nine items, each rated from 0 (no fatigue) to 10 
(worst imaginable fatigue). The total score ranges from 0 to 90, with higher scores 
indicating greater fatigue severity. The BFI-T has demonstrated excellent reliability, 
with a Cronbach’s α of 0.97 and test-retest reliability of 0.91 (Lin et al., 2006). 
Emotional Symptoms： 
Emotional distress was assessed using the Distress Thermometer (DT), a 
validated visual analog scale developed by Roth et al. (1988) to screen for distress 
caused by illness-related emotional issues such as anxiety, sadness, fear, and depression. 
Participants rate their level of distress on a scale from 0 (no distress) to 10 (extreme 

distress), with a score of 5 representing moderate distress. In clinical practice, a cutoff 
score of 4 is commonly used to indicate significant distress. The Chinese version of the 
DT was adapted from the version provided by the National Comprehensive Cancer 
Network (NCCN). Wang et al. (2011) reported a sensitivity of 98% and a specificity of 
73% for the DT. 
.Statistical Analysis 
All statistical analyses were performed using IBM SPSS Statistics version 26.0. 
To evaluate baseline homogeneity between the experimental and control groups, 
independent samples t-tests were used for continuous variables, while chi-square (χ²) 
tests or Fisher’s exact tests were applied for categorical variables, as appropriate. The 
effectiveness of the light therapy intervention on sleep quality, fatigue, and emotional 
distress across time points was assessed using generalized estimating equations (GEE), 
which account for correlated repeated measures and accommodate missing data. 
Statistical significance was set at a two-tailed p value of < 0.05. 
Results 
A total of 94 participants diagnosed with gynecologic cancer were enrolled and 
randomly allocated into the experimental and control groups with a 1:1 ratio (47 per 
group). During the study period, four participants withdrew due to health-related 
reasons, resulting in a final sample size of 90 (44 in the experimental group and 46 in 
the control group). The mean age was approximately 52 years. Baseline demographic 
and clinical characteristics were analyzed to ensure group equivalence. All variables 
were comparable between groups, except for body mass index (BMI), which showed a 
statistically significant difference and was adjusted for in subsequent analyses. 
Primary and Secondary Outcomes： 
Participants completed outcome assessments at baseline and weekly intervals for 
four weeks following the intervention (T1–T4).Sleep quality was assessed using the 

Insomnia Severity Index – Chinese version (ISI-C).Fatigue was evaluated using the 
Brief Fatigue Inventory – Taiwan version (BFI-T).Emotional distress was measured 
using the Distress Thermometer (DT).All instruments were administered at baseline 
(T0), and at days 7 (T1), 14 (T2), 21 (T3), and 28 (T4). 
Changes in these outcomes across timepoints and between groups were analyzed 
using generalized estimating equations (GEE), with BMI included as a covariate to 
adjust for baseline differences. This model allowed for evaluation of group, time, and 
interaction effects on outcome measures. 
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