Key Points:

New Zealand is in the grip of a hidden sleep epidemic that is costing the country billions of dollars, says an expert in sleep-related disorders.

Sleep expert Professor Philippa Gander said widespread sleep deprivation was "up there with the big public health epidemics" and the cost was counted in related health problems and lost productivity.

Lack of sleep was linked to diabetes, obesity, heart problems, strokes, hypertension and some cancers, she said. It was also one of the leading causes of car crashes, yet no public health funding was available to treat those with sleep problems.

Gander, who worked for Nasa researching flight crew fatigue and is now director of the Sleep/Wake Research Centre at Massey University in Wellington, said health authorities should not underestimate the cost of chronic sleep problems.

The "Wake Up Australia" study in 2004 estimated sleep disorders affected 6 per cent of Australians at a cost of $10.3 billion a year.

In New Zealand an estimated 5.6 per cent of 30 to 60-year-olds have obstructive sleep apnoea syndrome (they stop breathing and their sleep is interrupted), which is associated with high blood pressure, heart disease, stroke and motor accidents.

Maori and Pacific people are three times as likely to have sleep apnoea as the rest of the population.

Gander's team estimated that in 2004-5 it cost $94 to improve quality of life for a sleep apnoea sufferer, compared with the average amount Pharmac spent - $6865 - to gain one quality-of-life year improvement.

"It's a very, very cheap way of improving people's health but still we don't do it," said Gander.

Dr Tony Fernando, an Auckland psychiatrist who specialises in insomnia, estimates at least 10 per cent of the population has chronic insomnia (sleeping problems for more than a month). "You're talking about 400,000 New Zealanders." Massey's Sleep Wake Centre survey shows 37 per cent of adults aged 30 to 60 are sleep-deprived and 25 per cent of adults aged 20 to 60 have insomnia.

Gander has briefed the former Minister of Labour, Ruth Dyson, on sleep deprivation issues, including the lack of a systematic approach to treating insomnia and the lack of public health funding.

New Zealand has 20 clinical beds for diagnosing and treating sleep disorders, compared with 200 in Toronto, which has a similar-sized population. Available beds are not used to capacity because of caps on funding.

"We pay a high price for lack of sleep," Gander said. Medicine traditionally focused on "the waking two-thirds. We ignore the other third."

Gander said injury accidents on Auckland's roads could be reduced by nearly 20 per cent if people avoided driving when they were tired or had had less than five hours' sleep in the previous 24 hours.

Rotating shift work doubled the risk of a work-related injury. Multiple jobs, overtime and double shifts also contributed to lack of sleep.

Lifestyle, work habits and policy needed to change, Gander said.

"We need better information and public education about the actual costs of the choices we make. It's a big societal issue."

Labour Minister Trevor Mallard said there were real safety concerns about fatigue in the workplace.

Department guidelines on managing shiftwork and fatigue would be released before Christmas. They include advice on working a safe number of hours, recovery time between shifts, and training and education. Are we a tired nation? Insight, p32-34.