A gene that controls humans' sleeping habits has been discovered, claim scientists.
The protein, called ABCC9, can reduce the length of time we sleep.
Scientists said the same gene was previously linked to heart disease and diabetes.
The latest findings can explain why light sleepers, such as former British prime minister Margaret Thatcher, are able to manage with just four hours of sleep every night.
It was reported that the Iron Lady used to sleep just for four hours when she was in power.
Scientists conducted a study on 4,000 people from seven different EU countries who were asked to fill out a questionnaire assessing their sleeping patterns.
Answers of all the participants were analysed by scientists and their genes were studied.
The study concluded that people who had two copies of one common variant of ABCC9 slept for "significantly shorter" periods than people with two copies of another version, the Daily Mail has said.
The study carried out by scientists from the Ludwig Maximilians University of Munich has already proved that a gene similar to ABCC9 is also present in fruitflies.
The team said that they were able to modify it in the animal and shorten the length of time for which it slept.
"Apparently the relationships of sleep duration with other conditions such as heart disease and diabetes can be in part explained by an underlying common molecular mechanism," Dr. Karla Allebrandt, author of the report, has been quoted by the Daily Mail as saying.
"The ABCC9 gene is evolutionarily ancient, as a similar gene is present in fruitflies. Fruitflies also exhibit sleep-like behaviour."
"When we blocked the function of the ABCC9 homolog in the fly nervous system, the duration of nocturnal sleep was shortened."
"It is very encouraging for us that ABCC9 also affects the nocturnal sleep period in flies," said the co-author Prof.Till Roenneberg.
"This tells us that the genetic control of sleep duration may well be based on similar mechanisms in a wide range of highly diverse species."