Supplementary Material for: The Effect of Low-Dose Acetylsalicylic Acid on Cellular Immune Responses to Experimental Sleep Restriction in Healthy Humans

Introduction: Sleep deficiency is known to increase the risk for multiple disease conditions involving immunopathology, in which inflammation is thought to be a mechanism for disease development. Thus, one potential way to mitigate negative health consequences of deficient sleep is to target inflammation. We investigated whether low-dose acetylsalicylic acid (ASA, aspirin) administration prior to and during exposure to an experimental sleep restriction challenge affects cellular immune responses to sleep restriction. Methods: We studied 46 healthy humans (19F/27M, age range 19–63 years) in a randomized trial with 3 protocols each consisting of a 14-day at-home phase followed by an 11-day (10-night) in-laboratory stay (sleep restriction/ASA, sleep restriction/placebo, control sleep/placebo) with daily ASA (81 mg/day) or placebo intake across the entire study period (at-home and in-laboratory). During in-laboratory stays, sleep opportunity under both sleep restriction conditions was 8 h during 2 pre-challenge nights, 4 h during 5 nights of restricted sleep, and 8 h during 3 nights of recovery sleep. Under the control sleep condition, participants had a sleep opportunity of 8 h/night throughout the protocol. Blood samples were analyzed prior to and following 5 nights of sleep restriction/control sleep, and after 2 nights of recovery sleep. Data were analyzed using generalized linear mixed models. Results: Experimental sleep restriction increased WBC, lymphocyte, monocyte, eosinophil, basophil, CD4 T cell counts, and the CD4/CD8 T cell ratio compared to control sleep under placebo (p<.01). Low-dose ASA had no effect at pre-challenge for most cell types. However, low-dose ASA attenuated the eosinophil and basophil responses to sleep restriction and reduced elevation of the CD4/CD8 T cell ratio (p<.01). Monocyte counts stayed elevated after 2 nights of recovery sleep in the sleep restriction/ASA condition compared to control sleep, whereas monocyte counts recovered under placebo intake (p<.01). Conclusion: The present study shows that low-dose ASA can counteract certain cellular immune responses to sleep restriction, in particular elevations in eosinophil and basophil counts as well as the CD4/CD8 T cell ratio, while not affecting most immune cell counts prior to the sleep restriction challenge. Trial Registration: ClinicalTrials.gov NCT03377543.