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The modern 24-hour society poses challenges for adhering to a healthy sleep regime and light exposure pattern that can have implications for the development of employee mental health complaints such as burnout. In the Netherlands, one in five people report experiencing sleep-related problems, 41% of which indicated consequent impaired functioning at work (CBS and TNO, 2018). Several studies have already indicated that sleep may be an important mechanism for recovery from daily work demands, contributing to the restoration of energetic and motivational resources depleted throughout the day (Ekstedt et al., 2009; Geurts & Sonnentag, 2006; Sonnenschein et al., 2007). Good sleep could thus greatly support the ability to recover from daily demands at work by restoring psycho-physiological systems. On the other hand, daily sleep disruptions may impair the ability to recover from daily work demands and cause a depletion of energic and motivational resources (i.e., burnout-related symptoms) over time. Daily disruptions in sleep risk becoming chronic, potentially resulting in an erosion of energic and motivational resources (i.e. burnout). Furthermore, as one of the main indicators of solar time, light largely regulates the phase of our biological clock. Depending on the time of exposure, light can advance or delay circadian phase, impacting the regulation of a number of psychological and physiological processes during the 24-h day, including the timing of sleep on- and off-set (Baron & Reid, 2014). Electrical indoor lighting has allowed humans to extend their workday late into the night, threatening circadian phase delay (Wright et al., 2013) and increasing the potential to induce circadian misalignment (i.e., a mismatch between an individual’s circadian phase and actual sleep-wake timing). Moreover, persons are generally exposed to relatively low light levels during daytime (Smolders et al., 2013), especially compared to light levels outdoors, resulting in a weak signal for the biological clock. Therefore, inadequate light regimes during the workweek may negatively affect sleep-wake patterns and thus the ability to recover adequately from daily (work-related) demands. In addition, luminous exposure can also induce more acute effects on one’s daytime functioning such as enhancing alertness, vitality, and positive mood and reducing fatigue and sleepiness (Beute & de Kort, 2018; Smolders et al., 2012, 2013; Smolders & de Kort, 2014). On the other hand, a lack of energy and motivation may also disrupt sleep (possibly due to increased job stressors impairing recovery processes, i.e., the recovery paradox (Sonnentag, 2018) or due to the disruptive effect of stress on sleep (Åkerstedt et al., 2009)), and potentially disturb light exposure patterns in return by exerting additional strain on the recovery mechanism (Meijman & Mulder, 1998). As sleep disruptions contribute to a lack of energy and motivation (Åkerstedt et al., 2009), and a lack of energy and motivation may potentially disrupt sleep, a vicious cycle is triggered causing a progressive depletion of energy and motivation over time. Nevertheless, how and to what extent disturbances in sleep and light exposure regimes contribute to this downward spiral of energy and motivation erosion (i.e. development of burnout-related complaints over time) is largely unknown. Additionally, the role that a depletion of energy and motivation plays in the temporal development of sleep disturbances is similarly unclear. This study aims to investigate how and to what extent sleep (disturbances) (Part A) covary with markers of burnout (i.e., depletion of energy and motivation levels; Demerouti et al., 2001) over a long time period, and whether the degree of disturbances in a healthy sleep regime can predict the depletion of energy and motivation (burnout) at a later stage and vice versa. To clarify these relationships across different timeframes (ranging from days to months, seasons and a year), we take a longitudinal approach. We complement longitudinal with daily measures to also account for and assess the daily relationship between sleep and energy and motivation. This provides insights regarding daily mechanisms, allowing for the assessment of possible changes in the daily relationship between sleep, energy and motivation over time (i.e. throughout burnout development). Thereby we gain insights into the stability of these daily relationships and can assess whether the development of sleep (disturbances) and/or the depletion of energy and motivation is reflected within days as well. Additionally, we consider the role of daily light exposure patterns (Part B) in sleep and daily energy and motivation. As a secondary objective, we aim to explore (Part C) several work-related mechanisms (job demands, perseverative cognition, recovery, need for recovery/fatigue at the end of the workday) that have implications for sleep, energy and motivation, and may thus contribute to the downward spiral of energy and motivation erosion over time.