BACKGROUND: Sleep is vital for mental health, physical health, quality of life, and safety. Firefighters are at a higher risk for chronic sleep disruption due to a combination of factors including rotating 24-hour on and 48-hour off work schedules, unpredictable and hazardous work obligations, and/or traumatic events experienced while on shift. Tryptophan is an amino acid found in peanuts that has been positively associated with sleep quality due to its influence on melatonin and serotonin levels in the body. Therefore, the purpose of this study was to determine the effect of consuming peanut butter at night on aspects of sleep in shift-working firefighters. METHODS: 40 firefighters participated in this 8-week study and were randomized into a peanut butter group (n=20) or control group (n=20). An Actigraph GT3X sleep and activity wristwatch was worn for 8 weeks to assess sleep quality and quantity. Participants of both groups completed a baseline week of normal living before beginning the 7-week intervention. During the intervention, both groups were asked to stop eating two hours before bedtime. The peanut butter group was asked to consume a serving of peanut butter two hours before bedtime for five nights a week. SPSS version 29 was used to analyze the variables latency, efficiency, time in bed, time asleep, time until first awakening, number of awakenings, and time spent awake via separate linear mixed-effects models. Individual subjects were specified as a correlated random effect. Averages for each week were computed and designated as the repeated measures variable Time with 8 points (baseline and weeks 2-8). The fixed factors were Time and Group (peanut butter or control). RESULTS: There appeared to be a significant effect of Time on latency, F7, 154.77 = 2.71, p = .011, which was higher at week 8 (23.35 min, CI95% = 13.43-33.23 min) than at baseline (8.98 min, CI95% = 1.91 - 16.04 min). However, no time point differences were significant following Bonferroni adjustments. There were no main effects of Time or Group, or interaction effect, on any of the other variables. CONCLUSION: Peanut butter did not alter sleep variables compared to the control group in this study, nor were the sleep variables impaired by peanut butter consumption. However, the data does demonstrate abnormal sleep patterns of firefighters and further research is needed to find simple strategies to improve sleep in this population. Grant Information: The Peanut Institute funded this study.

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