Josh Friedman , 2025-05-06 18:47:00
Key takeaways:
- Personalized light interventions from a wearable device and app significantly decreased cancer-related fatigue.
- Participants had decreased daily and weekly fatigue in the randomized trial.
Personalized recommendations on light exposure may significantly reduce fatigue for patients with cancer, according to results of a randomized trial.
Participants who received assistance, including blue-light blocking glasses and unique daily light interventions based on wearable data, reported lower weekly and daily fatigue over 12 weeks.
Sung Won Choi
“Wow! A noninvasive, wearable sensor just extracting heart rate can inform how I should do certain behaviors of my day, and it can actually have health benefits without a prescribed pill? That is really amazing,” Sung Won Choi, MD, MS, Edith S Briskin and Shirley K Schlafer Foundation Research Professor of Pediatrics at Michigan Medicine, told Healio. “I was floored. I was so excited that we could see results like this. This study offers an exciting glimpse into the potential benefits of personalized light exposure in reducing fatigue for patients with cancer.”
“Before I was a grad student studying this, I didn’t think light did anything to your body. Now, I’m the craziest light enthusiast you’ll ever meet,” Olivia Walch, PhD, adjunct research investigator in the department of neurology at Michigan Medicine and CEO of Arcascope, added.
“I dim the lights at my friend’s house, and I go out of my way every day to get as much light as I can, because it’s, functionally, a drug that you ingest through your eyes. The more people become aware of this, the more visible we make the downstream effects of light exposure.”
Fatigue is a ‘huge problem’
Walch, a circadian mathematician, did not intend to investigate the impact of light intervention on cancer-related fatigue when she began her studies.
She planned to evaluate whether the circadian clock, which regulates the body’s processes over roughly 24-hour cycles, could have any impact on the way physicians time drugs.
“I went into a conversation with some oncologists, and the response overwhelming was, ‘Timing drugs differently, maybe that could help, but what every single one of our patients has right now is fatigue,’” Walch said. “Fatigue is such a huge problem, and we know it’s related to sleep. We know it’s related to circadian rhythms. Why don’t you try tackling that first?”
People with cancer can experience fatigue for multiple reasons, including the malignancy itself, treatment or psychological factors, according to study background.
Additionally, disruption of the circadian clock can cause adverse events such as sleep disruption, metabolic issues and mood disorders.
“There’s a ton of connections between circadian rhythms and fatigue,” Walch said. “Clocks get thrown out of whack, and they can get into this lasting state of being out of whack for a really long time, where sleep is chronically disrupted. Then, even if [someone does] get 8 hours in a night, they still feel very flat and bad.”
Studies of light interventions on cancer-related fatigue have previously been conducted, including one that showed 30 minutes of bright white light could reduce fatigue, but those are “one-size-fits-all approaches,” lead author Caleb Mayer, PhD, postdoctoral researcher at Stanford University, told Healio.
Mayer, Walch, Choi and colleagues aimed to see if personalized recommendations could make a bigger difference.
Assessing fatigue
Researchers included adults diagnosed with breast or prostate cancer, or a hematologic malignancy requiring hematopoietic stem cell transplant, in their study.
They randomly assigned participants to intervention and control arms. The final analysis included 65 patients (mean age, 58.9 years; range, 19-87; 53.8% women; 92.3% white) in the intervention arm and 66 (mean age, 59.2 years; range, 25-76; 53% women; 89.4% white) in the control.
All patients received an Apple watch, which recorded their wearable data.
Those in the intervention arm received blue-light blocking glasses and the Sync app, which gave them daily, personalized recommendations on light exposure based on their wearable data.
They received four categories of interventions: seek bright light, seek super bright light, put on blue-light blocking glasses or be in the dark.
The control arm received fake blue-light blocking glasses and a sham app, which gave recommendations that would have a low impact on their circadian clock.
“[The intervention arm] wouldn’t see the same thing every day,” Walch said, noting they received an average of roughly four recommendations per day. “They might be told to move to light earlier or later, and it was all about responding to the signals we were getting from [the watch].”
All patients received a daily, one-question survey asking, “How fatigued are you?” They could respond, “Not at all fatigued,” “A little bit fatigued,” “Somewhat fatigued” or “Very fatigued.” They also received a once-weekly fatigue questionnaire.
Weekly self-reported fatigue scores served as the primary endpoint. Daily fatigue scores served as the secondary endpoint.
‘Super cool’ results
Participants in the intervention arm had a significant reduction in their weekly fatigue scores — from 56.1 at week 1 to 52.86 at week 11 (–3.23 points; P = .015).
The control arm also had a decrease from 55.17 to 52.63 (–2.54 points), but it did not reach statistical significance.
Patients in the intervention arm had a greater reduction in weekly fatigue scores compared with the control arm across cancer types.
The intervention arm had a larger decrease in daily fatigue scores from week 1 to week 12 compared with the control arm (–0.34 vs. –0.19), as well.
The two groups did not have significantly different fatigue scores at the start or end of the trial. However, the intervention arm had significantly lower scores at week 12 compared with week 1 (P = .002). The control arm did not.
“You’re taking a drug related to fatigue right now. In this instant you’re taking it, and it’s light exposure,” Walch said. “Your body really does process light exposure like a drug. It has a chemical effect on your body. People don’t think about it as dosing, but at night, if you keep the lights on a little later, or during the day you don’t get as much light as you normally do, those are things having real chemical effects on your body.”
Researchers acknowledged study limitations, including lack of confirmation on how often individuals legitimately followed recommendations.
“I didn’t expect the clear glasses to do anything [for the control group]. I didn’t expect the dummy recommendations to do anything, but we’re giving them an Apple watch,” Walch said. “That thing is going to tell them to walk 10,000 steps a day. It’s going to tell them to go to bed at the same time every night independent of our app.
“Whenever I look at that daily fatigue, and I see it start to split apart, it makes me really happy because it shows that it wasn’t just having a wearable [prompt of], ‘Go walk,’ or, ‘Get into bed.’ It was the value added of personalized light recommendations that explains the difference between those two [arms]. I think that’s super cool.”
‘Outstanding investment’ with ‘significant return’
Walch highlighted multiple areas of future research involving light exposure, including its effect on fatigue within different cancer types.
Though patients in the intervention arm had greater fatigue reductions across cancer types in the trial, the differences between malignancies stood out.
Men with prostate cancer had their scores drop 1.91 points, but individuals with hematologic malignancies saw their scores fall 4.39 points.
“Are some cancer types — and more broadly, some diseases — more responsive to circadian interventions for fatigue?” Walch asked.
Researchers also could investigate circadian rhythms outside of adult cancer, such as among children or people with multiple sclerosis.
Finally, Walch wants to see if circadian rhythms can affect health in other ways.
“Your circadian clock isn’t just deciding if you’re tired or not,” Walch said. “It’s affecting the amount of DNA repair you do. It’s affecting the amount of cortisol in your body. These things have implications for how well your drug might work. I really want to start using this technology in patients actively on treatment and trying to see if we can better characterize how people respond to treatments.”
Researchers want to improve the functionality of the app, too.
“The version we tested in this study, it was cute,” Walch said. “We’re not using any psychology hacks to promote engagement. We tell people this is what they should do, and we hoped they did it. I think there’s a lot of room to improve, not that people need little digital points to do a positive thing in their life, but it taps into the parts of our brain that respond to dopamine and reward stimuli.”
The app and results impressed Choi enough that she is promoting light interventions with her patients.
“The educational benefit that patients are getting by being informed about how light could affect their sleep or how they feel [is substantial],” she said.
“This could be offered to people in every state,” Choi added. “It’s just an outstanding investment with a significant return. While the results are promising, I’m cognizant that this is an early study. I look forward to future, larger trials that will help validate these findings.”
For more information:
Sung Won Choi, MD, MS, can be reached at sungchoi@med.umich.edu.
Caleb Mayer, PhD, can be reached at mayercl@umich.edu.
Olivia Walch, PhD, can be reached at olivia@arcascope.com.
Sources/Disclosures
Collapse
Disclosures:
Walch reports being CEO of Arcascope, speaking events for and honorarium and travel expenses from Unilever, and consulting for Gideon Health. Choi and Mayer report no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
