Viruses can cause severe infections if they are contracted early in the morning, according to researchers from the University of Cambridge. A new study suggests that “the early bird catches the worm” idiom should be changed to “the early bird catches an infection.”

A team of researchers at the Wellcome Trust-Medical Research Council Institute of Metabolic Science, from the University of Cambridge, suggested that individuals are prone to infections due to viruses’ replication and spread between cells. The body clock plays a role in the ability of replicating and spreading viruses throughout the body at specific times of the day. As per scientists, the body clock acts like a 24-hour cycle of physiological processes, these phenomena are called “circadian rhythms

Morning Person
Once a virus enters the body, the machinery, and resources in human cells are forced to stop the reproduction and spread of the virus’ effects. Image credit:

The role of circadian rhythms

Circadian rhythms are in charge of controlling the body’s physiology as well as several functions (sleep patterns, body temperature, immune systems) depending on the time of the day. In general terms, circadian rhythms are controlled by numerous genes, including Bmal1 and Clock. Researchers focused this time on gene Bmal1, whose climax activity is centered in the afternoon.

The study assessed how circadian rhythms become susceptible or contribute to the progression of body’s infections. Researchers infected wild-mice type with influenza and herpes virus during different parts of the day and placed them into controlled environments. Each mice was exposed to 12 hours of daylight and 12 of of nightlight. Researchers measured levels of virus replication and spread in mice’s organism.

Morning person
Viruses need all body’s mechanisms in the best conditions at the right time to attack cells. Even a tiny infection could be quickly spread throughout the body, causing severe diseases. Image credit:

The new findings, published in the medical journal PNAS on Monday, pointed out that mice infected with a virus in the morning had ten times higher viral levels compared to mice infected during late hours. The reason, researchers explain, lays on the interaction existing between the viruses’ mechanism and body’s functions.

The same experiment was repeated on mice lacking the Bmal1 gene and higher levels of virus spread regardless the period of time when the infection was contracted.

Because the body is more active during daylight times, viruses take advantage of this feature in order to easily infect the body. Viruses have the ability of replicating and reproducing throughout the body by infecting a host cell, according to researchers.

Further on, apart from the 24-hour cycle, researchers discovered that Bmal1 gene also goes through seasonal variation. The gene showed less activity in winter than in summer times. The discovery might explain why viruses such as influenza, are more common during winter.

“The time of day of infection can have a major influence on how susceptible we are to the disease, or at least on the viral replication, meaning that infection at the wrong time of day could cause a much more severe acute infection. This is consistent with recent studies which have shown that the time of day that the influenza vaccine is administered can influence how effectively it works,” remarked Professor Akhilesh Reddy, the study’s senior author.

Disrupted body clocks as the perfect environment for viruses  

The study also revealed that infected mice with their body clock disrupted presented also the perfect environment for viruses to attack their immune systems.

According to Dr. Rachel Edgar, the study’s first author, each cell presented in the body has a biological clock to control body’s functions as well as to look forward to every single change in the body’s mechanism.

Morning Person
Shift workers are more prone to contract infections and develop severe health conditions, including chronic diseases. Image credit: RD

Dr. Edgar remarked that the study’s findings entail the job of body’s clock while determining viruses’ multiplication. The scientist also said that when the body clock is disrupted in human’s or mice cells, the result is the same when it comes to viral replication.

“When we disrupted the body clock in either cells or mice, we found that the timing of infection no longer mattered – viral replication was always high. This indicates that shift workers, who work some nights and rest some nights and so have a disrupted body clock, will be more susceptible to viral diseases. If so, then they could be prime candidates for receiving the annual flu vaccines,” said Edgar.

Source: University of Cambridge (Press Release)