London: Having sleep problems? Consult a doctor, for a new study says that lack of shut eye every night can damage your immune system and make you ill.

Researchers at Yale University have found that the circadian clock the genetic mechanism which regulates our sleep controls the level of a gene vital to human immune system, a magazine reported.

They have based their findings on an experiment on laboratory mice.

The researchers linked the gene TLR-9 to the cycle in mice. When the gene was at its most active, it was able to respond best to bacteria and viruses and the mice responded better to infection and vaccinations.

In theory, the principles should also apply for the same gene in humans, say the researchers claiming that disruptions to the cycle can make people more susceptible to illness.

This suggests that jet lag may contribute directly to illness and that there may be ideal times of the day to receive vaccinations, they claim.

Prof Erol Fikrig, who led the study published in the 'Immunity' journal, said: "People intuitively know that when their sleep patterns are disturbed, they are more likely to get sick."

However, he said that further study was needed into how noise and artificial light in intensive care units could be affecting patients.

Prof Fikrig added: "Sleep patterns of patients in intensive care are often disrupted because of the noise and prolonged exposure to artificial light. It will be important to investigate how these factors influence immune system response."