Image caption The study involved more than 150,000 people

The belief that older people tend to suffer worse sleep may be false - in fact the reverse may be true, according to US researchers.

A telephone survey of more than 150,000 adults suggested that, apart from a blip in your 40s, sleep quality gets better with age.

Those in their 80s reported the best sleep, says the study in Sleep journal.

A UK sleep researcher said while poor health could affect sleep, it was a "myth" that age alone was a factor.

While universities have equipment which can measure sleep duration and disturbance in study volunteers, this does not always match the volunteer's own opinion on their night's rest.

The research, conducted by the Center for Sleep and Circadian Neurobiology at the University of Pennsylvania, instead focused on asking large numbers of randomly selected people about their sleep.

They were also asked about their race, income, education, mood and general health.

While being depressed or having health problems was linked to poor sleep quality, once the researchers had adjusted the results to compensate for this, a distinct pattern emerged.

Instead, they found that complaints about poor sleep quality fell as age rose, with the lowest number of complaints coming from the over-70s.

Middle age blip

The only exception to this trend was middle age, where sleep quality was poorer.

Dr Michael Grandner said the original reason for setting up the study was to confirm the precise opposite - that sleep quality declined in old age.

He said: "These results force us to re-think what we know about sleep in older people - men and women."

He suggested that it was possible that older people were sleeping worse, but simply felt better about it.

"Even if sleep among older Americans is actually worse than in younger adults, feelings about it still improve with age."

Professor Derk-Jan Dijk, Professor of Sleep and Physiology and Director of the Surrey Sleep Research Centre, said the study was "interesting".

He said: "We have got to get away from all these myths about ageing - many people are very content with their sleep."

However, he said that asking people for their subjective opinion about sleep patterns could produce answers that were dependent on their mood at the time.

"If you are angry because your boss didn't give you a pay rise, your perception of sleep quality may be very different from someone who is feeling generally content."