by Marwan Hamed, MPH

Oh, depression! The sorrowing lows! The disorder affecting so many, but understood by so few!

In fact, depression impacts so many people globally that the World Health Organization estimates that the global economy suffers a loss of about 1 trillion US dollars per year from lost productivity. With about 20% of employees in industrialized countries working in shift-based jobs, it’s important to figure out if and how work schedules could be affecting health ― and a big part of health is related to our moods. In fact, there’s convincing information showing that shift work is linked to anxiety, depression, and other mental illnesses. 

Sarah L. Chellappa, MD PhD, is a sleep researcher and chronobiologist at Harvard ― an expert who studies the human body’s natural daily rhythms. She is looking for the best ways for shift work to be more livable.

In a recent issue of European Journal of Neuroscience, she presented new scientific evidence ― including surveys, lab studies, and animal models ― showing how shift work creates disruptions in the biological clock that controls our circadian rhythms. Here we’re talking about the body’s natural and internal sleep-wake clock being linked to mood vulnerability in shift workers. This is by far most true for night shift workers, who tend not to get enough sleep during the day or night. They’ve got important stuff to do, and it’s simply hard to sleep naturally during the day . . . and, well, they have to work at night. This all puts a toll on the biological clock, leading to multiple negative health effects, including physical illness such as diabetes, heart problems, and cancers.

Lab studies show that biological clock disruptions can change mood levels and the brain activity behind moods, increasing the likelihood of depression, or worsening depression for those that already have it. Would you like to read more into these studies? Here are the links: studies 1, 2, and 3. On top of this, an animal study showed that biological clock disruptions in mice, mimicking those caused by shift work in humans, lead to changes in certain parts of the gut needed for natural mood management. Yes, the gut! This study helps show how our mood depends on connections between the gut and the brain. Another animal study showed that disruptions of the biological clock can seriously mess up how closely the brain and gut are able to manage moods.

Rotating Work Shifts, Chronotype, and Sleep

Now let’s consider the effects on sleep of chronotype, work shift type, and the interaction between the two. Researchers enlisted 74 police officers that had rotating morning, evening, and night work shifts. They were able to show a link between chronotype, work

 shift type, and sleep behavior ― including greater napping when workers rotated into the night shift. The clear lesson is that work schedules should cater to a person’s chronotype to reduce negative health effects.

So, if someone is more a “morning person” it only makes sense that working the morning shift would be better for them ― and vice versa for late chronotypes.

Shedding Some Light on Those Dark Night Shifts

If you’re reading this and you’re starting to get anxious and are thinking, “OK, Marwan, great! So now I’ve got to quit my job! But ― oh wait ― how will I pay my bills without a job?!” Well, hold on just a second. You see, there’s actually good news coming out of these studies! After all, if the studies didn’t shed light on the problem, it would be impossible to begin working on solutions.

And, when you get a bunch of experienced professionals together, sometimes they can come up with very healthy and helpful recommendations for taming the shift work blues, such as targeted light therapy, or a new look at meal timing ― important for the gut, which in turn is important for your brain and mood. These new practices could counteract the disruptive effect of shift work on the biological clock. And that would mean better productivity — better mood ― better sleep ― and better quality of life!

So, if you’re struggling with any kind of mood problem, talk to a mental healthcare professional, because the source of the problem may be in your work schedule, and there could be positive treatment options that spell a solution.

Marwan Hamed is a freelance writer for CET.