Night shifts are not just a development of modern life. For centuries, sailors, soldiers, bakers and innkeepers have had to be awake and working while others slept, but it was the Industrial Revolution and the grueling restructuring of the workday accompanying it that heralded a much wider adoption of night-shift work. In hospitals, public services, service industries and retail industries, shift work is not uncommon. Most employees who work the night shift choose to do so, but they may not realize what the toll of working while the world sleeps can take on their mental health.
Risks Associated with Night Work
Shift work has long been understood to increase risk factors for a list of health complications. According to an article in the journal, “Occupational and Environmental Medicine,” cardiovascular disease, fatigue, insomnia, obesity, stress and anxiety have all been linked to higher rates among shift workers, as has depression. It is not for certain yet if it is the night-shift hours themselves that cause depression or, because shift workers are mostly self-selected, if shift workers are simply more inclined to neurological problems. However, night-shift work may be linked with depression because of the disruption of certain biological processes, such as the circadian rhythms.
About Circadian Rhythms
All human vital signs, including our sleeping and waking cycles, are regulated by circadian rhythms. These are regular periods of change that fluctuate through the day and are important for correct bodily functioning; these rhythms are controlled by an internal clock and influenced by external cues to start or cease different functions. The most powerful of these external cues are light and darkness. Humans are evolutionarily designed to wake at sunrise and sleep at sunset, and prolonged exposure to bright lights at night and darkness in the day can throw off these rhythms.
Mental Effects of Light and Darkness
A long-acknowledged form of depression is related to a lack of light stimulus during the day. Seasonal affective disorder, common in regions with extremely short days in the winter, is directly linked to circadian rhythms being interrupted by too-short light periods; treatment using bright light therapy is effective in resolving the disorder. A study conducted by researchers at John Hopkins University testing the effects of disruptive light/dark cycles on mice revealed that the mice responded with depression-like symptoms when exposed to light or darkness in alternating 3.5 hour cycles. This suggests that shift workers struggling to sleep in darkened rooms during the daytime and working in brightly lit environments at night are pitting their internal and external circadian rhythm factors against each other, producing a kind of depressive state similar to seasonal affective disorder.
How to Manage Night Work
Shift workers are advised to adjust their schedules and lives to work with their circadian rhythm cycles as much as possible. If light levels at work are a controllable factor, use only what is needed to see: the less light exposure, the better. If possible, work night shifts on a permanent basis rather than on-again, off-again; given a sufficient amount of time, the body’s circadian rhythms will eventually adapt to being awake at night and reduce the symptoms associated with shift work. If permanent shift work isn’t an option, consider doing shift work either in large blocks of time, such as a few months at a time, to prevent the need to constantly shift rhythms, or else work as few night shifts in a row as possible — preferably only one — to maintain a diurnal operating schedule. Regardless of shift worked, physical exercise has conclusively shown to reduce depressive symptoms; night-shift workers prone to depression would benefit from a regular exercise regimen and a healthy diet.