A disrupted body clock may weaken the immune system, according to a new study published on Thursday.

Researchers have known that the body’s circadian clock is a finely tuned genetic mechanism in charge of regulating body functions that follow a 24-hour cycle, like sleep cycles and metabolic changes throughout the day, however the latest findings suggest that the time of the day could play a significant role in heightening the risk of getting an infection.

Researchers at Yale School of Medicine found that the circadian clock controls the activity of key Toll-like receptor 9 that responds to the presence of DNA from bacteria and viruses, in mice.

The immune system response to vaccination and the ability to resist infection were the greatest, when the TLR-9 levels were at their highest point in mice, investigators discovered.

Scientists also noted that previously it was found that people with sepsis, a severe condition in which the bloodstream is overwhelmed by bacteria that can originate from anywhere in the body, were more likely to die in the early hours of the morning, between 2am to 6am.

People with rheumatoid arthritis also display differences in symptom severity depending according to time of day, exhibiting the highest levels of inflammatory markers at night.

Researchers said that they had discovered a "direct molecular link between circadian rhythms and the immune system", which could have "important implications for the prevention and treatment of disease,” according to the study.

Study author Erol Fikrig, professor of epidemiology and microbial pathogenesis, said that although people have intuitively known that they when their sleep patterns are disturbed they are more likely to get sick, and now the study findings appears to give evidence that “disruptions of the circadian clock influence” does in fact increase the “susceptibility to pathogens”.

Researchers said that that jet lag may directly contribute to infections or illnesses when traveling, and also that there may be better times in the day to get vaccinated.

"When you get a vaccine today, it's when the doctor is available. We don't think about whether it should be given at 9 a.m. or 5 p.m. for best effect," Fikrig told MedPage Today.

"Further investigations now should look at immune recognition markers in humans to see when they peak and when they have their nadir," he added.

The findings are published online in the journal Immunity.