From dawn till dusk: Shedding light on the recovery process by investigating daily change patterns in fatigue.

Although the notion that recovery is a process rather than a state lies at the heart of recovery theory, the continuous cycle of depletion and replenishment of resources itself has not yet been investigated empirically. In the present article, I therefore build on recovery theory and on evidence from chronobiological research and adopt a temporal research approach that allows investigating change trajectories in fatigue over the course of the day. Furthermore, the role of sleep quality and psychological detachment in these change trajectories is investigated. Hypotheses are tested in an experience-sampling study involving 133 employees who were asked to provide fatigue ratings 4 times a day over 5 consecutive workdays. Growth curve analyses revealed that on average fatigue decreased in the morning, reaching a nadir around midday and then increased until bedtime. Additionally, daily sleep quality explained variation in individuals' fatigue change trajectories: When sleep quality was low, next day fatigue decreased between morning and midday and then increased again until bedtime; when sleep quality was high, fatigue remained stable until midday and then increased again between the end of work and bedtime. Theoretical implications for the recovery literature and practical implications are discussed in conclusion. (PsycINFO Database Record