Eating at night harms the heart

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Going to the fridge at night apparently damages the heart. This is shown by a US experiment that simulated two weeks of shift work. Negative effects were seen in the heart rate and inflammation parameters. Both increase the risk of heart disease.

“In industrialized countries, around 15 percent of the working population works night shifts. It increases the risk of cardiovascular disease,” concludes the study recently published in the journal Nature Communications. Among other things, a longer duration was associated with a higher incidence of coronary heart disease in people who were observed for 24 years. According to the team led by Sarah Chellappa from Brigham and Women’s Hospital in Boston, the increased risk cannot be fully explained by differences in lifestyle and socioeconomic status.

The scientists tested the effect of shifted circadian schedules on healthy volunteers (seven women and twelve men with an average age of 26.5 years and normal weight) in an experimental setup. “This consisted of a 14-day circadian laboratory protocol to test the effects of simulated night work with eating either at night and during the day or only during the day on the chronobiological rhythm of cardiovascular function compared to simulated daytime work,” the study states.

Different meal times
First, all test subjects had to stay awake for 32 hours and were given a snack every hour. Typical night shifts were then simulated. During this time, some of the test subjects were always allowed to eat. This also applied to the night. The other half was only allowed to eat during the day as a comparison group. The duration of sleep was the same in both groups.

Extensive medical tests were carried out in parallel to the experiment. The researchers measured various cardiovascular risk factors, including markers of the autonomic nervous system, plasminogen activator inhibitor 1 (PAI-1; which increases the risk of blood clots), and blood pressure.

These cardiovascular risk factors increased after simulated night work compared to baseline in participants who were able to eat during the day and at night. However, in the study participants who only ate during the day, the risk factors remained the same, although the amount and content of the diet did not differ. The only difference was the timing of food intake.

Heart rate variability decreases
For example, the so-called heart rate variability decreased, which indicates a disturbance of the recovery function via the nervous system (parasympathetic nervous system). In addition, a significant increase in the concentration of the PAI-1 protein in the blood was registered. This is associated with an increased risk of blood clots forming in veins or arteries.

According to the authors, the study could explain the increased incidence of cardiovascular disease among shift workers. Eating at night has negative effects.