(PS3-59) The (Lack Of) Relationship Between Eating Timing, Fasting Duration, and Depression: Implications for Time-restricted Eating as a Zeitgeber

The circadian rhythm is a 24-hour cycle that regulates various molecular and physiological processes. Zeitgebers, such as light exposure and dietary patterns, are behavioral circadian cues that are essential in synchronizing these rhythms. Time-restricted eating (TRE), a dietary intervention limiting food intake to specific hours of the day, has been posited as a potential zeitgeber with the hypothesis that the fasting period could improve circadian regulation. Many studies have demonstrated medical benefits to TRE (Chaix et al., 2019; Sutton et al., 2018) and others have shown enhanced circadian regulation via TRE’s fasting period in Drosophila (Ulgherait et al., 2021). Though it is plausible that TRE and the associated fasting period may also improve psychological outcomes such as sleep quality and depression through circadian regulation (Jaffe & McGlinchey, 2024), no human-subjects studies have looked at the psychological impacts of TRE or its mechanisms. Given the high prevalence of both sleep disorders and depression (Merikangas et al., 2010), using relatively simple interventions such as TRE can help treat a far broader range of people who might otherwise face barriers to improvement.

We surveyed 1,256 people (55.8% female; 27.5% non-White) using Connect (an online participant recruitment platform; Hartman et al., 2023). We measured the timing of meals and snacks using the Food Timing Screener (Chakradeo et al., 2022), sleep disturbance using the PROMIS Sleep Disturbance and Sleep-Related Impairment scales (Yu et al., 2011), and depression using the Hamilton Depression Inventory (Reynolds & Kobak, 1995). We calculated the length of the main fasting period by measuring the time between the last eating event at night (either dinner or a snack) and the first eating event the following day (either breakfast, lunch, or a snack).

The distributions of all self-report measures followed expected patterns, and eating timing was predictably shifted later on weekends than during the week. There were weak associations between the latest time that people ate and sleep disturbance (r = .10, p = .01), sleep-related impairment (r = .11, p = .001), and depression (r = .08, p = .01). Despite earlier research suggesting that the duration of the fasting period is associated with circadian enhancement, we did not find any associations between the duration of the fasting period and sleep disturbance (r = .00, p = .91), sleep-related impairment (r = -.03, p = .38), or depression (r = .00, p = .91). These associations remain null even after considering the moderating effects of biological rhythms (chronotype) and morning/evening preference. While TRE may offer certain health advantages, its effectiveness as a zeitgeber that can be leveraged in therapy to improve sleep and depression remains uncertain. Though they are observational, our findings suggest caution in assuming that the circadian mechanisms that are impacted by TRE in animal studies carry over to humans.