Feeling tired? Obesity and depression are among the reasons why people are getting poor sleep, even if they're spending plenty of time in bed.

Good quality sleep has a lot to do with life out of bed, new research shows.

Lifestyle factors including obesity, shift work, depression and socio-economic status, have been identified as common risk factors for poor sleep.

Measures to combat the curse of unsatisfying slumber need to consider more than just time spent in bed, James Cook University researcher Yaqoot Fatima said on Wednesday.

She has led a study examining the results of a sleep data from 41,000 middle-aged people over a six-year period.

"Around one third of the study participants who reported sleeping for the recommended duration, nonetheless reported considerable burden of sleep problems and daytime sleepiness," Dr Fatima said.

About 40 per cent of those surveyed were found to be 'healthy sleepers', with about 32 per cent 'borderline poor sleepers' and 28 per cent 'poor sleepers'.

Low socio-economic status, unhealthy lifestyle, poor health, and depressive symptoms were significantly linked to poor sleep.

"Over the six years of follow-up there were indications that poor sleep is a relatively stable phenomenon, rather than something that will just go away by itself in time," Dr Fatima said.

"This tells us early intervention is crucial for sleep improvement and it's important that we do so as evidence consistently highlights the rising prevalence of poor sleep and its role in the growing burden of chronic health conditions."