What else did it find?
The research also noted that consistent over-long sleeping (more than nine hours a night) can be a cause for concern. While lengthy sleeping does not in itself increase the risk of death, it can be a significant marker of an underlying serious and potentially fatal illness.
How was it compiled?
The report reviewed 16 prospective studies from the UK, US, European and East Asian countries. It included more than 1.3 million participants, followed for up to 25 years, with more than 100,000 deaths recorded.
The results of the research were sent out to healthcare correspondents. University of Warwick comms manager Kelly Parkes-Harrison handled the PR support.
The release gained initial coverage on 1-2 May in all the nationals except the Financial Times, and was repeated later in the week in The Sun, The Daily Telegraph and The Times in relation to the amount of sleep the political party leaders were getting during the election campaign. It was also featured on BBC Breakfast and Radio 4's Today programme, and had global pick-up in Australia and Japan.
- 73% higher risk of being overweight if you sleep less than four hours a night
- 25% higher risk of being overweight if you sleep less than six hours a night.