JMIR Publications

ABSTRACT

Background:

Fatigue is one of the most common symptoms treated in primary care and can lead to deficits in mental health and functioning. Light therapy can be an effective treatment for symptoms of fatigue, but the feasibility, scalability, and individual-level heterogeneity of light therapy for fatigue are unknown.

Objective:

The current study evaluates the feasibility, acceptability, and effectiveness of a series of personalized (N-of-1) interventions for virtual delivery of bright light (BL) therapy and dim light (DL) therapy versus usual-care (UC) treatment for fatigue in 60 participants.

Methods:

Participants completed satisfaction surveys comprised of the System Usability Scale (SUS) and items assessing satisfaction with the components of the personalized trial. Symptoms of fatigue were measured using the PROMIS daily, PROMIS weekly, and ecological momentary assessment (EMA) questionnaires delivered three times daily. Comparisons of fatigue between BL, DL, and UC treatment periods were conducted using Generalized Linear Mixed Model (GLMM) analyses between participants and generalized least squares (GLS) analyses within individual participants.

Results:

Participants rated the usability of the personalized trial as acceptable (average SUS score=78.9) and 92% (N=49) of those who completed satisfaction surveys (N=53) stated they would recommend the trial to others. Levels of fatigue symptoms measured using the PROMIS daily fatigue measure were lower or improved in BL [B(95% CI) = -1.63 (-2.63 to -0.63)] and DL [B(95% CI) = -1.44 (-2.50 to -0.38)] periods relative to UC. Treatment effects for BL and DL on the PROMIS daily measure varied between participants. Similar findings were demonstrated for the PROMIS weekly and EMA measures of fatigue symptoms.

Conclusions:

Participant scores on the SUS and satisfaction surveys suggest that personalized N-of-1 trials of light therapy for fatigue symptoms are both feasible and acceptable. Both interventions were found to produce significant reductions in participant-reported fatigue symptoms relative to usual care. However, the heterogeneity of these treatment effects across participants showed the effect of light therapy is not uniform. This heterogeneity along with high ratings of usability and satisfaction support the use of personalized N-of-1 research designs in evaluating the effect of light therapy on fatigue for each patient. Further, the results of the current trial provide additional support for the use of series of personalized N-of-1 research trials. Clinical Trial: This trial is registered in www.ClinicalTrials.gov (number NCT04707846).