Studies: Shift work leads to fatal heart diseases

Constantly changing working hours disrupt our circadian rhythm
Many people in Germany work as shift workers. The constant change of working hours disturbs the daily rhythm. This often causes sleep problems and other health problems. Researchers have now found that shift workers have an increased risk of heart disease due to their irregular working hours.

Scientists from Northwestern University in Chicago have now discovered that abnormal sleep patterns in shift workers disrupt the body's natural rhythm. As a result, those affected have an increased risk of developing heart diseases. The doctors published the results of their study in the journal "Hypertension".

Shift work puts a strain on our health and our social life
Shift work poses an increased health risk compared to working with regular working hours. This risk increases when night work is included, the experts say. For this reason, medical checks are even mandatory for night workers in many countries. Continuous shift work is physically very stressful and also hinders our social activities, such as sports and dealing with friends and family. Our rest periods are often also affected. For example, the sleep after a night shift is usually shorter and worse than a normal night sleep, the doctors explain. The new study now found that an abnormal sleep cycle increases the risk of heart disease, especially for shift workers.

Shift work can cause a so-called circadian misalignment
Almost all physiological and behavioral processes that are regulated by an internal clock in our brain, especially the sleep-wake cycle, are influenced by the so-called circadian rhythm, explains the lead author Dr. Daniela Grimaldi. If our sleep-wake and nutritional cycles are out of tune with the rhythm of our internal clock, a circadian misalignment can occur, adds Dr. Grimaldi added.

Study among people with insufficient sleep or delayed sleep times
The results of the new study suggest that shift workers are chronically exposed to the circadian offset. The rotation of the shift work means that the regenerative cardiovascular effects of nighttime sleep cannot be optimally exploited, explain the experts from Northwestern University in Chicago. The small study included 26 healthy people aged 20 to 39 years. All subjects either achieved only five hours of sleep a day for a period of eight days or experienced a shift in sleep times of 8.5 hours in four out of eight nights, the scientists say.

Fatigued people produce large amounts of the stress hormone norepinephrine
In both groups, an increased heart rate was found during the day. This increased even further at night, when sleep deprivation was combined with delayed bedtime, the researchers warn. There was also an increase in the stress hormone norepinephrine in the overtired group with the delayed bedtime. The researchers explain that norepinephrine can constrict the blood vessels in the body, raise blood pressure and expand the trachea.

Decreased bedtime reduces the activity of the vagus cranial nerve
Deprivation of sleep and delayed bedtime went hand in hand with reduced heart rate variability at night, the experts explain. In addition, a reduction in the activity of the so-called vagus cranial nerve could be determined when those affected were in deeper sleep phases. These deep sleep phases usually have a strengthening effect on our heart functions. The main effect of the vagus nerve on our heart is to lower the heart rate, the study authors explain. Shift workers should definitely be encouraged to eat a healthy diet and sufferers need to exercise regularly and try to get extra sleep to better protect their hearts, the researchers add. (as)

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