Is It Harmful To Work At Night?

It’s been revealed what harm night shifts at work can do to your health.

People have been working at night since time immemorial. For instance, our grandfathers and grandmothers used to work in factories during the night shift, while their children were put to work in special 24-hour kindergarten groups. Nowadays, night work also exists – according to statistics from the Higher School of Economics, 64% of people work in the evening, at night or on weekends. 


The sleep-wake cycle has long evolved to allow people to live actively during the day and rest at night. There is even a concept in science called the “circadian clock”, which refers to the brain function that keeps track of the amount of visible light at each moment of life. That is, when light begins to fade, the internal clock notices this and triggers a surge of melatonin in the brain. It is this substance that gives the body the signal to go to sleep. Melatonin levels remain high at night, but drop at dawn and remain low during the day.

During the day, levels of other chemicals (neurotransmitters), such as norepinephrine and acetylcholine, rise in the body and keep people awake. This system ensures that the body is in sync during the day-night cycle. Many other body functions, including temperature, digestion, heart rate and blood pressure, fluctuate during the day depending on circadian rhythm activity.

An important body function related to circadian rhythms is internal body temperature. It rises during the day, then reaches a low point in the early morning, then peaks again towards evening.

The tendency to fall asleep and continue sleeping through the night occurs during a phase of decreasing circadian temperature between midnight and 4am. That is, when the body temperature rises, it becomes increasingly difficult to stay asleep. This is one of the reasons why night workers, who try to fall asleep at 8am, find it very difficult to do so, and also find it difficult to stay in bed and sleep in the middle of the day.

What happens? A person who works at night or starts his workday before 6am goes against his circadian rhythm. This can put him or her at risk for health problems. Research shows that night work can be dangerous to your health.


A person who works the night shift disrupts their circadian rhythms and is at risk of all kinds of health problems:

  • Increases the likelihood of obesity
  • Increases the risk of cardiovascular diseases.
  • Mood swings begin to change frequently
  • Gastrointestinal problems start to emerge, for example stomach discomfort and flatulence
  • Psychological problems arise, leading to conflicts and quarrels, and divorces
  • increased risk of cancer and, in the case of women, breast cancer.
  • Sleep deprivation caused by night work may increase the risk of epilepsy in people with a predisposition
  • Night workers with diabetes may have difficulty controlling blood sugar levels.


Shift workers sleep an average of two to three hours less than other workers. They often sleep in two shifts during the day: a few hours in the morning and then an hour or so before going to work at night. Night workers may find it difficult to sleep during the day. And it is generally difficult to maintain a dark, silent and relatively cool environment for sleeping in the middle of the day. 

It takes the body about 10 days to adjust to working the night shift. However, workers on this shift often revert to daytime routines for a day or two at the weekend, making the circadian rhythm unstable.


The number of hours in a shift (8 or 12) is also debatable. It can be said that 12-hour shifts are easier on the body. However, it is important that when you change the 12-hour shift schedule, overtime is not allowed. Another risk to sleep occurs when a worker who works seven 12-hour shifts a week uses their free time for other employment. Some night shift workers may experience pronounced daytime sleepiness.