Department of Biobehavioral Health, Pennsylvania State University, State College, PA, USA.
Department of Oncology and Division of Psychosocial Oncology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
J Psychosom Res. 2020 Dec;139:110266. doi: 10.1016/j.jpsychores.2020.110266. Epub 2020 Oct 6.
Altered diurnal cortisol rhythms are a potential mechanism through which symptoms of fatigue are maintained in post-treatment cancer survivors. Exposure to early morning bright light may target this underlying dysregulation, resulting in improved diurnal cortisol patterns, subsequently improving symptoms of fatigue. This research investigates the effects of a 4-week light therapy intervention on the diurnal cortisol slopes and output in fatigued cancer survivors.
Post-treatment adult cancer survivors who met diagnostic criteria for cancer-related fatigue were randomly assigned to receive either a bright white light (BWL) or dim red light (DRL) device, used daily for 30 min over four consecutive weeks. Assessments of fatigue and salivary cortisol were collected at baseline and post-intervention. Cortisol was sampled four times per day (waking, noon, 5 pm, bedtime) for three days at each timepoint. Diurnal cortisol slopes and total cortisol output were calculated at baseline and post-intervention. Linear mixed models were used to analyze the data.
Seventy-seven participants were included in this analysis (BWL n = 40; DRL n = 37). Participants in both groups displayed increased steepness in cortisol slope (B = -0.02, p = .01, Cohen's d = 0.57) and increased total cortisol output (B = 9.58, p = .03, Cohen's d = 0.49) from baseline to post-intervention, indicating only a moderate effect of time. Neither diurnal cortisol slopes nor total cortisol output mediated the relationship between the light therapy intervention and fatigue levels.
Though the results of this trial are promising for light therapy as an effective intervention to reduce fatigue in cancer survivors, this does not appear to be achieved through alterations in neuroendocrine function. ClinicalTrials.gov registration #: NCT01780623.
昼夜皮质醇节律的改变是导致治疗后癌症幸存者持续出现疲劳症状的潜在机制。清晨暴露于明亮的光线可能会针对这种潜在的失调进行治疗，从而改善昼夜皮质醇模式，进而改善疲劳症状。本研究调查了为期 4 周的光照疗法干预对疲劳的癌症幸存者昼夜皮质醇斜率和输出的影响。
符合癌症相关疲劳诊断标准的治疗后成年癌症幸存者被随机分配接受明亮白光（BWL）或暗淡红光（DRL）设备治疗，每天使用 30 分钟，连续 4 周。在基线和干预后评估疲劳和唾液皮质醇。在每个时间点的三天内，每天四次（醒来、中午、下午 5 点、睡前）采样皮质醇。在基线和干预后计算昼夜皮质醇斜率和总皮质醇输出。线性混合模型用于分析数据。
本分析纳入了 77 名参与者（BWL 组 n=40；DRL 组 n=37）。两组参与者的皮质醇斜率（B=-0.02，p=0.01，Cohen's d=0.57）和总皮质醇输出（B=9.58，p=0.03，Cohen's d=0.49）均从基线增加，表明只有时间的中度影响。昼夜皮质醇斜率和总皮质醇输出均不能介导光照疗法干预与疲劳水平之间的关系。
尽管该试验的结果表明光照疗法作为一种有效干预措施，可降低癌症幸存者的疲劳，但这似乎不是通过改变神经内分泌功能来实现的。临床试验注册编号：NCT01780623。
