Do sleep, stress, and illness explain daily variations in fatigue? A prospective study

ObjectiveFatigue is related to a number of serious diseases, as well as to general well-being. It is also a major cause of sickness absence and use of health facilities. Still, the determinants of variations in fatigue are little investigated. The purpose of present study was to investigate the relationships between the daily variations of fatigue with sleep during the previous night, stress or disease symptoms during the same day — across 42 consecutive days of normal life.Methods50 individuals participated and gave diary reports and used an actigraph across the 42 days. The data was analyzed using a multilevel approach with mixed model regression.ResultsThe analyses showed that the day-to-day variation in fatigue was related to (poor) sleep quality (p < .001) and (reduced) sleep duration (p < .01) the previous night, as well as to higher stress (p < .05), and to the occurrence of a cold or fever (p < .001) during the same day as the fatigue rating. Fatigue was also strongly related to poorer subjective health (p < .001) and sleepiness (p < .001) during the same day.ConclusionThe results indicate that prior sleep (and sleepiness) as well as stress and illness are consistently connected to how fatigue is experienced during normal living conditions.