A new study, led by scientists from the University of Bristol and the University of Occupational and Environmental Health in Japan, delves into the impact of 'circadian misalignment.' This phenomenon, often associated with 'jet lag' and known to disrupt the body's natural rhythm, was examined in terms of how it affects the hormones responsible for regulating appetite.
The research published in the journal Communications Biology reveals that circadian misalignment can have a profound effect on the brain's ability to control hunger-related hormones, particularly damaging metabolic health, which is a concern frequently observed among individuals who work night shifts.
Jet Lag Disorder: A Disruption to Circadian Rhythm
Jet lag, a temporary sleep disruption, affects individuals who rapidly travel across multiple time zones due to the misalignment between their circadian rhythms and the local time at the destination. The severity of jet lag often increases with the number of time zones crossed, with eastward travel causing more pronounced symptoms, and recovery typically takes about a day per time zone crossed.
Circadian misalignment leads to a range of symptoms, including sleep problems, daytime fatigue, cognitive impairments, gastrointestinal issues, discomfort, and mood fluctuations.
These symptoms tend to worsen with increased time zone crossings and are especially noticeable during eastward travel. During this adjustment period, various bodily functions, such as sleep-wake cycles and eating habits, remain out of sync with the local schedule.
One key factor in mitigating jet lag is exposure to natural light, which plays a pivotal role in regulating circadian rhythms. Light influences the production of melatonin, a hormone responsible for coordinating various physiological functions in the body.
This hormone typically diminishes with the onset of daylight, and being exposed to light at the right times can assist in adjusting to the new time zone more effectively. However, the timing and duration of light exposure are crucial to ensuring a successful transition.
Night Shift Work and Appetite: How Circadian Misalignment Affects Eating Patterns
The researchers focused on glucocorticoid hormones in the adrenal gland, which play a role in various physiological functions, including metabolism and appetite regulation. These hormones directly influence a group of brain peptides controlling appetite behavior, with some increasing appetite (orexigenic) and others decreasing appetite (anorexigenic).
In an animal experiment involving control and 'jet-lagged' groups, the team observed that the misalignment between light-dark cues led to dysregulation of orexigenic hypothalamic neuropeptides (NPY) in the 'jet-lagged' group. This resulted in a significantly increased desire to eat during the inactive phase of the day, compared to the control group.
Remarkably, the control group rats consumed 88.4% of their daily intake during their active phase and only 11.6% during the inactive phase. In contrast, the 'jet-lagged' group consumed 53.8% of their daily calories during their inactive phase, without any increase in activity during that time, amounting to nearly five times more (460%) than the control group's consumption during the inactive phase. These findings highlight the impact of circadian misalignment on the timing of food consumption.
The findings reveal the significant impact of circadian misalignment on neuropeptides when daily glucocorticoid levels are not synchronized with light-dark cues, potentially offering targets for drug treatments to address eating disorders and obesity.
Recommendations for night shift workers include maintaining daylight exposure, participating in cardiovascular exercise, and following regulated meal schedules.
However, the researchers acknowledge the difficulty of overriding internal brain signals driving increased appetite with discipline or routine and are planning further studies to investigate rescue strategies and pharmacological interventions to mitigate caloric overconsumption linked to chronic stress and sleep disruption.
RELATED ARTICLE: Early Birds Tend To Earn More Than Night Owls: Study Links Circadian Rhythm to Income
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