Different color temperature on the effectiveness of rehabilitation training in patients with ischemic stroke：A prospective, single-center, randomized controlled clinical trial
Authors: Wang Nan , Xue Yan , Wang Tongyue , Qiu Fengxi , Li Cheng , Wang Zhiyuan , Jiang Jianke , Lu Yi , Shao Yingqi , Bai Zhongfei , Lan Danmei , Hu Qilong , Wu Hengjing 
Published: November 2024

Background: Stroke is a leading cause of death and disability worldwide, especially in China, where its incidence is rising. Post-stroke rehabilitation is crucial for restoring neurological function and improving quality of life. Light therapy, a non-pharmacological intervention, is gaining attention for its potential to promote neuroplasticity and enhance brain circulation. Warm and cold light, differing in color temperature, have shown benefits in improving sleep, neurological recovery, and emotional well-being in stroke patients, though their mechanisms are not fully understood. This study explores the effects of different light color temperatures on stroke recovery to optimize rehabilitation approaches.
Methods: A randomized controlled trial conducted at the Shanghai Yangzhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center) (Chinese Clinical Trial Registry: ChiCTR2200057541).
48 patients with ischemic stroke were randomly divided into three groups (1:1:1): warm light group (WLG, 500 lx, 3000 K, n=16), cold light group (CLG, 500 lx, 6500 K, n=16), and control group (CG, 500 lx, 5000 K, n=16). Participants underwent 60 minutes of rehabilitation therapy daily from Monday to Friday, between 8:30 AM and 9:30 AM, in different color temperature light environments. The primary outcome was the National Institutes of Health Stroke Scale (NIHSS). Secondary outcomes included the Short Form-36 (SF-36), Self-Rating Sleep Scale (SRSS), and levels of interleukin 6 (IL-6), norepinephrine (NE), and melatonin (MT).
Results: The study found that the CLG (-2.00(2.75), p＜0.001) out-performed WLG (-0.00(1.75), p = 0.003) and CG (-0.00(0.00), p＜0.001) in NIHSS scores. There was also a significant decrease in SRSS scores in the CLG (-5.50(5.50), p＜0.001) compared with WLG(-1.00(3.00), p=0.026) and CG(-1.00(3.00), p=0.040). SF-36 assessments indicated better management of role limitations due to significant improvements in energy/fatigue levels in the CLG (5.00(13.75), p=0.011) compared with WLG (p <0.001) and CG (p <0.001)), and superior social functioning compared to both WLG (p <0.001) and CG (p =0.001). In terms of pain, the CLG showed a significant improvement (32.50(15.50), p=0.016) compared to WLG (p=0.032) and CG (p=0.007). For general health, the CLG showed positive changes (p=0.009). The results were significant improvement in health change within the CLG compared to the CG (p=0.002). Lastly, MT levels in the CLG (-4.13±5.10, p = 0.006) significantly decreased compared with WLG (p = 0.018). No significant changes in NE and IL-6 levels were observed across all groups, and no apparent adverse events were reported.
Conclusions: Cold light therapy showed significant improvement in multiple indicators, particularly in NIHSS, SRSS, and SF-36's energy/fatigue, pain, and health change aspects, and also demonstrated a reduction in MT levels. These results indicated the substantial potential of cold light therapy as an adjunct treatment for accelerating neurological rehabilitation and managing related complications in ischemic stroke.
Trial registration: Chinese Clinical Trial Registry, number: ChiCTR2200057541. Registered March 14, 2022.