Effects of a light therapy intervention on diurnal salivary cortisol in fatigued cancer survivors: A secondary analysis of a randomized controlled trial

Cancer related fatigue-light therapy: updated meta-analysis of randomised controlled trials

BACKGROUND

Moderate-to-severe cancer related fatigue occurs in 45% of patients with cancer and interferes with many aspects of quality of life. Although physical exercise has level 1 evidence for improvement of cancer related fatigue, it has a relatively high behavioural demand compared with other non-pharmacological interventions. The aim of this updated meta-analysis was to address the efficacy of light therapy in improving cancer related fatigue in patients with cancer.

METHODS

We included randomised controlled trials investigating the efficacy of bright white light (BWL) therapy in ameliorating cancer related fatigue in patients with cancer. This meta-analysis was conducted using a random-effects model. The target outcomes were changes in cancer related fatigue associated with BWL or dim red light (DRL).

RESULTS

There were 9 articles with 231 participants included. The main results revealed that daily morning BWL for 30 min was associated with significantly better improvement in fatigue severity compared with DRL (k=5, Hedges' g=-0.414, 95% CI -0.740 to -0.087, p=0.013). The subgroup without psychiatric comorbidities (k=4, Hedges' g=-0.479, 95% CI -0.801 to -0.156, p=0.004) was associated with significantly better improvement in fatigue severity with BWL than with DRL. In contrary, BWL was not associated with significantly different changes in depression severity or quality of life compared with DRL. Finally, BWL was associated with similar acceptability (ie, dropout rate) and safety profile (ie, any discomfort) as those of DRL.

CONCLUSIONS

This meta-analysis provides an updated evidence on the rationale for application of BWL in ameliorating cancer related fatigue in patients with different types of cancer.

TRIAL REGISTRATION NUMBER

INPLASY202140090.

The Effect of Bright White Light on Fatigue Levels in Patients with Gynecological Cancer: A Randomized Control Trial

Objectives: Bright white light (BWL) therapy is one of the non-pharmacological methods in the management of fatigue. The aim of the study was to evaluate the effect of BWL on fatigue levels in patients with gynecological cancer who were receiving chemotherapy. Methods: This randomized controlled study were made with 72 women (intervention (n:36) and control (n:36) groups) at gynecologic oncology clinic. Standard BWL at the intensity of 10,000lux was applied to the patients in the intervention group at the same time every day between the second and the eighth days of the chemotherapy cycle. Fatigue levels of all patients (n: 72) were evaluated on the first,ninth and 21st days. Results: The first, ninth, and 21st days general fatigue scores of intervention and control groups was 4.876 ± 0.000;4.384 ± 0.270;4.387 ± 0.258 and 4.876 ± 0.000;5.033 ± 0.270;4.984 ± 0.258, respectively (p = 0.100). Interference of fatigue with daily life scores was found statistically different between the intervention and control groups in the first, ninth, and 21st day, respectively 4.55 ± 0.26; 3.53 ± 0.23; 3.57 ± 0.22 and 4.95 ± 0.26;4.79 ± 0.23;4.82 ± 0.22 (p = 0.029). Conclusions: BWL therapy was effective in reducing interference of fatigue with daily life in patients receiving chemotherapy, but did not affect the general fatigue level of the patients. Based on the available data, it is possible that the application of BWL may have a positive effect on general fatigue when the number of samples and the application time are increased. Trial Registration: ClinicalTrials.gov Identifier: NCT05009693.

The Influence of Light Wavelength on Human HPA Axis Rhythms: A Systematic Review

Environmental light entrains many physiological and behavioural processes to the 24 h solar cycle. Such light-driven circadian rhythms are centrally controlled by the suprachiasmatic nucleus (SCN), which receives information from the short-wavelength-sensitive intrinsically photosensitive retinal ganglion cells. The SCN synchronizes local clocks throughout the body affecting sleep/wake routines and the secretion of neuroendocrine-linked hormones such as melatonin from the pineal gland and cortisol via the hypothalamic pituitary adrenal (HPA) axis. Although the effects of light parameters on melatonin have been recently reviewed, whether the experimental variation of the spectral power distribution and intensity of light can induce changes in cortisol rhythms remains unclear. Thus, this systematic review evaluated the effects of daytime exposure to lights of different spectral wavelength characteristics and luminance intensity on the cortisol levels in healthy individuals. A search of the PubMed, Web of Science, EMBASE, CINAHL, Medline, PsycINFO and Cochrane Library databases on 19 June 2023 identified 3418 articles, of which 12 studies (profiling 337 participants) met the inclusion and risk of bias criteria. An analysis of the literature indicated that exposure to bright lights of any colour during the late night or early morning can induce significant increases in cortisol secretion relative to time-matched dim light comparison conditions. Furthermore, exposure to bright lights with stronger short-wavelength (blue/green) components in the early morning typically induced greater increases in cortisol relative to lights with stronger long-wavelength (red) components. Thus, the circadian regulation of cortisol is sensitive to the wavelength composition of environmental lighting, in line with the more commonly studied melatonin. As such, wavelength characteristics should be optimized and reported in light intervention studies (particularly for the investigation of cortisol-associated disorders and HPA axis function), and exposure to short-wavelength light during sensitive periods should be carefully considered in constructed environments (e.g., bedroom and classroom lighting and device screens).

Light Therapy for Cancer-Related Fatigue in (Non-)Hodgkin Lymphoma Survivors: Results of a Randomized Controlled Trial

Simple Summary

Cancer-related fatigue (CRF) is one of the most frequently reported symptoms with prevalence rates of 25 to 60 percent in (non-)Hodgkin lymphoma survivors. Several (pilot) studies showed promising effects of light therapy to reduce CRF. The aim of the current study is to evaluate the short- and long-term efficacy of light therapy on CRF and associated symptoms in chronically fatigued (non-)Hodgkin lymphoma survivors. Eighty-three survivors were exposed to bright white light (intervention) and another 83 survivors were exposed to dim white light (comparison). Results showed that all participants, irrespective of light condition, reported reduced levels of fatigue after the completion of light therapy. Similar results were found for depression, sleep quality, and some aspects of quality of life. No effect was found on circadian rhythms or objectively assessed sleep. Therefore, it is important to further investigate which aspects of intervention are associated with the improvements observed after light therapy.

Abstract

Purpose: To evaluate the short- and long-term effects of light therapy on fatigue (primary outcome) and sleep quality, depression, anxiety, quality of life, and circadian rhythms (secondary outcomes) in survivors of (non-)Hodgkin lymphoma presenting with chronic cancer-related fatigue. Methods: We randomly assigned 166 survivors (mean survival 13 years) to a bright white light intervention (BWL) or dim white light comparison (DWL) group. Measurements were completed at baseline (T0), post-intervention (T1), at three (T2), and nine (T3) months follow-up. A mixed-effect modeling approach was used to compare linear and non-linear effects of time between groups. Results: There were no significant differences between BWL and DWL in the reduction in fatigue over time. Both BWL and DWL significantly (p < 0.001) improved fatigue levels during the intervention followed by a slight reduction in this effect during follow-up (ES_T0-T1 = −0.71; ES_T1-T3 = 0.15). Similar results were found for depression, sleep quality, and some aspects of quality of life. Light therapy had no effect on circadian rhythms. Conclusions: BWL was not superior in reducing fatigue compared to DWL in HL and DLBCL survivors. Remarkably, the total sample showed clinically relevant and persistent improvements on fatigue not commonly seen in longitudinal observational studies in these survivors.