Biorhythm: Virus infections are much more risky in the morning

Virus infections: time of day affects susceptibility to diseases
According to British researchers, the time of day when people come into contact with viruses plays a significant role. In one study, they found that biorhythm appears to affect susceptibility to disease. The new findings may be useful in choosing when to vaccinate.

Some people tend to get sick
Although every person can become infected with countless pathogens, some tend to get sick, while others almost never. This is partly due to the fact that some people are more susceptible to infections. For example, because her immune system is weakened due to a lot of stress or an unhealthy diet. The severity of an infectious disease is not the same for all patients. Why this is so could possibly be due to the timing of the infection, as British researchers have found.

The time of infection affects the severity of an illness
The team of scientists found that the time of day plays an important role in the severity of a viral infection. Her investigation shows that herpes viruses multiply drastically faster in mice if the animals become infected at the beginning of their resting phase.

As the team led by Professor Akhilesh Reddy from Cambridge University in the UK wrote in a statement from the university, the discovery could partly explain why the time of day also plays a role in vaccinations, why shift workers are susceptible to diseases or why infectious diseases are more likely to occur in winter.

"Infection at the wrong time of day could cause a much more severe acute infection," the study authors said. The results of the investigation were published in the "Proceedings" of the US National Academy of Sciences ("PNAS").

Virus levels ten times higher
As the professional association of pediatricians (BVKJ) writes on its website "", viruses - in contrast to bacteria and parasites - depend on infiltrating a foreign cell in order to multiply. However, the cells go through certain changes over the course of a day - the pattern they follow is also known as the “internal clock”.

In their investigation, the British researchers infected mice with either the flu or the herpes virus. It was found that the animals that came into contact with the viruses in the morning had a virus level ten times higher than those that were infected in the evening. "The virus attempted to take a factory after all workers went home was a failure," said Professor Akhilesh Reddy in an interview with the BBC. The time of day makes a big difference. In the case of pandemics, for example, it might matter whether people stayed at home during the day.

Why are certain diseases more common in winter?
Around ten percent of the genes change their activity depending on the "internal clock" during the day and thus the instructions they give to the body. According to the BVKJ, the scientists focused on a gene that determines this internal clock, the Bmal1.

This gene shows the highest activity in both mice and humans in the afternoon. In the morning, when living things are particularly susceptible to infections, the activity is least. The gene also shows less activity in humans in the winter months - possibly an explanation for why people are more prone to infections during this time of year. However, there could be other explanations for this.

Scientists from Cambridge University reported last year in the journal "Nature Communications" that our immune system changes with the seasons. According to the experts, their discovery offers a possible explanation for the fact that certain diseases occur more often or worse in winter and that people tend to stay healthy in the summer months.

Flu shot in the morning more effectively
According to the study authors, the results of the current study could also explain why shift workers whose body clocks are disturbed are susceptible to chronic diseases, possibly also to viral diseases. In addition, the effectiveness of vaccinations could depend on the time of day. This was recently pointed out by a study in people aged 65 and over.

The team led by Anna Phillips from the British University of Birmingham reported in the journal “Vaccine” that flu vaccinations in the morning compared to those in the afternoon boosted the production of antibodies more within a month. (ad)

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Video: Experiments to shed light on the seasonality u0026 pathogenicity of CoV-2 and other respiratory viruses (January 2022).