New York, Jan 28 (IANS): People who are deprived of sleep regularly are likely to have a weak immune system, a study has found.

The findings showed that chronic short sleep shuts down programmes involved in immune response of circulating white blood cells.

Seven or more hours of sleep is recommended for optimal health, thus the immune system functions best when it gets enough sleep, the researchers said.

"The results are consistent with studies that show when sleep deprived people are given a vaccine, there is a lower antibody response and if you expose sleep deprived people to a rhinovirus they are more likely to get the virus," said lead author Nathaniel Watson, University of Washington in Seattle.

For the study, published in the journal Sleep, the team took blood samples from 11 pairs of identical twins with different sleep patterns and discovered that the twin with shorter sleep duration had a depressed immune system, compared with his or her sibling.

They used identical twins because genetics account for 31 to 55 per cent of sleep duration and behaviour and environment accounts for the remainder.

"Modern society, with its control of light, omnipresent technology and countless competing interests for time, along with the zeitgeist de-emphasising sleep's importance, has resulted in the widespread deprioritisation of sleep," the researchers noted.