London: Finding it hard to drag yourself out of bed in the morning? Blame it on your genes, scientists say.
Researchers at the Edinburgh University in the UK found that a variation of a gene called ABCC9 could explain why some people need more shut-eye.
The variant of ABCC9, which one in five Europeans carry, is involved in sensing energy levels of cells in the body.
And those with this "sleep switch" need almost 30 minutes more rest each night than those without, the researchers said.
The findings, they said, will help future sleep studies establish how the gene variant regulates sleep duration, reported a daily.

For the study, published in journal Molecular Psychiatry, the researchers along with a team from Ludwig Maximilians University of Munich examined genes in fruit flies and human sleep patterns.
Flies without the ABCC9 variant slept for three hours less than normal, while humans with it slept for longer than the "average" eight hours.
More than 10,000 people throughout Europe who took part in the study provided information on how many hours they slept each night and a blood sample to analyse their DNA.
Sleep was measured on "free days" -- when people did not need to get up for work the next day, take sleeping pills or work shifts.
Study researcher Dr Jim Wilson of Edinburgh University said: "I was staggered when we found this gene variant, given the obvious health difficulties people suffer as a consequence of a lack of sleep.
"You have to understand a problem before you can do something about it. Hopefully more genes will now be discovered and this can also lead to us dealing better with the connected health issues."
Researchers also found the length of time people slept for often ran in families, despite the fact that the amount of sleep people need can be influenced by age, latitude, season and circadian (24 hour) rhythms.
Dr Wilson said he believed the study would help reveal the health effects of different sleep behaviours.
"I don't think it’s as simple as people with the gene going to bed 30 minutes earlier but today we are a step closer to tackling the problems for people who struggle to sleep," he added.