In a surprise twist, a recent study has found that there are actually some benefits to sleeping in: your body is more susceptible to viruses in the morning.
According to a study from the University of Cambridge, viruses can be up to 10 times more dangerous if they infect patients in the morning, suggesting that it might not always be best to get out of bed early — especially if it means exposing yourself to viruses.
In the study, published in the medical journal PNAS on Monday, mice were infected with either influenza, the virus that causes flu, or herpes, the virus that can cause a range of diseases, including cold sores. In the end, researchers found that mice infected with viruses in the morning had 10 times the viral levels of those infected in the evening.
The reason why this is the case is because of the unique interaction caused by the mechanisms of viruses and the body.
Viruses, unlike bacteria or parasites, are independent particles that are only capable of replicating by infecting a host cell. Before doing so, they lack many properties of living things and so are not considered to be alive.
Meanwhile, the human body follows a circadian rhythm, which is an approximately 24-hour cycle of physiological processes that is commonly referred to as the body clock. During this cycle, different functions of the body are more active, depending on the time of day. In the case of this study, researchers looked at one gene called Bmal1, which has its peak activity in the afternoon in both mice and people.
The result of this interaction is as clear as day (or morning, in this case): since the body is more active during the day, viruses have an easier time infecting the body during that period. Conversely, later in the day, when the body is less active, viruses aren't able to infect the body as easily.
"The virus needs all the apparatus available at the right time, otherwise it might not ever get off the ground, but a tiny infection in the morning might perpetuate faster and take over the body," said Prof. Akhilesh Reddy, one of the researchers who took part in the study.
Interestingly enough, the study also found that viruses are particularly effective when the mice had their body clocks disrupted.
"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," said Dr. Rachel Edgar, another researcher who took part in the study. "If so, then they could be prime candidates for receiving the annual flu vaccines."
The team hopes that this study will help in controlling viral outbreaks, such as Ebola in West Africa or Zika in Latin America.
"In a pandemic, staying in during the daytime could be quite important and save people's lives, it could have a big impact if trials bear it out," Reddy added.