AnnaMarie Houlis

The city is swathed in dark skies when Terry Lynne Garvey’s alarm clock wakes her at 5:30 pm. Her phone, blinking with messages, is all that lights up the bedroom of her Upper East Side apartment when she rolls out of bed. She pours herself a cup of tea, responds to the texts and emails she’d missed throughout the day and catches up with her roommate before throwing on her scrubs, meeting her coworkers at Starbucks and heading to the hospital together.

Garvey is a registered nurse in the Neuro Intensive Care Unit at the NYU Hospital in midtown Manhattan — she’s also a night shifter who works from 8 pm to 8:30 am, which means that her bedtime is somewhere around 9:30 am depending on whether or not she gets out on time. She works three to four night shifts a week, which she tries to schedule back to back to avoid a feeling similar to being “jetlagged all the time,” she explained. 

“We make the best of it and taking care of patients is why we do it,” she said. “My manager and the hospital also support us in all ways possible. My manager is very flexible with our schedules — we do self-scheduling and can kind of pick the days we work. Plus, we have a lot of sick time and always have an open door policy if we need anything. But I couldn’t do it without the help and support from my coworkers, truly. We all work together at night.” 

Though she sleeps at night on her days off, working nightshift is no easy feat. Working through the night and other alternative shifts inevitably takes a toll on the health of the more than 15 million full-time workers who aren’t daytime desk jockeys. In 2007, the World Health Organization (WHO) classified nightshift work as a potential carcinogen due to its disruption of the body’s circadian rhythm (the “body clock”), which can, in turn, cause a host of health issues and complications.

For women, in particular, working nightshifts can cause particularly precarious effects. Here’s how nightshift can hurt women’s health.

1. Working nightshifts tends to lead to poor sleep quality and, therefore, impaired brain functionality.

In 2007, a study in the journal SLEEP found that shift workers, in general, are more likely to experience lower serotonin levels than non-shift workers, which could thereby impact sleep. And another 2012 study found that police officers on nightshifts are actually 14 times more likely to be sleep deprived because they get fewer than six hours of sleep a day.

Of course, sleep deprivation is a common factor behind a spectrum of other issues, too. It can actually cause parts of the brain’s synapses to be “eaten” by other brain cells, according to a 2017 study by researchers at the Marche Polytechnic University in Italy. Astrocytes — abundant glial cells in the brain that clean out worn-out cells and debris so electric impulses can be transferred smoothly between neurons — are more active when we’re deprived of sleep, so they break down more of the brain’s connections than necessary. Microglial brain cells, which account for around 15 percent of all brain cells, are also more active during chronic sleep deprivation, and sustained microglial activation has been observed in Alzheimer’s and other neurological disorders.

The results of an older 2014 study also found that participants who were currently working or who had previously worked shifts scored lower in tests assessing memory, processing speed and overall brain power than participants who worked traditional daytime hours.

2. There’s a link between nightshifts and cancer for women.

Research from 61 articles comprising 114,628 cancer cases and 3,909,152 participants from North America, Europe, Australia and Asia has found that working nightshifts could heighten the risk of skin cancer by 41 percent, breast cancer by 32 percent and stomach cancer by 18 percent. The findings showed that an increased risk of breast cancer was only found among female nightshift workers in North America and Europe, and female nurses on nightshift had a 58 percent increased risk of breast cancer, a 35 percent increased risk of gastrointestinal and a increased 28 percent risk of lung cancer, compared to non-nightshift workers. 

Working nights raises a woman’s risk of breast cancer by 30 percent, according to a 2012 study published in the International Journal of Cancer. A 2013 study also found that women who work nights may be more likely to develop ovarian cancer.

3. Nightshifts can cause depression.

Shift work of all kinds can increase the risk of mental health problems, due to the disruption in the circadian system, which regulates the release of different hormones in the body. And depression is already more prevalent in women than in men. A 1997 study published in the International Journal of Occupational and Environmental Health supports that shift work increases the lifetime risk of major depressive disorder (MDD). In 2008, more research published in the International Journal on Disability and Human Development discovered that “shift work is suggested to increase the risk of developing or aggravating mood disorders at least in vulnerable individuals.”

4. Night shifters have a higher risk of metabolic problems.

Metabolic problems may be a result of insufficient sleep, which can change one’s appetite. This is because shift workers tend to have irregular eating habits and therefore some might develop poorer diets, both of which can increase the risk of metabolic problems.

Nightshift workers also tend to have higher levels of triglycerides than day workers, the main constituents of body fat in humans. A 2009 study published in the journal, Proceedings of the National Academy of Sciences, found that they also have lower levels of leptin, which is the hormone that regulates weight and affects blood sugar and insulin levels.

5. Working nightshifts can lead to an array of heart issues.

Shift work takes a toll on the heart and can increase the likelihood of heart attacks, according to a review of research published in the British Medical Journal. Working the nightshift could account for ischemic strokes and coronary events, as well.

Likewise, circadian disruption has been observed to affect blood pressure and blood lipids levels (like cholesterol), which consequentially increases the risk of cardiovascular disease (CVD).


AnnaMarie Houlis is a multimedia journalist and an adventure aficionado with a keen cultural curiosity and an affinity for solo travel. She's an editor by day and a travel blogger at by night.