More than a third of Kiwis aren't getting enough sleep – something that may be an overlooked factor in New Zealand's poor rates of mental health.

A new study suggests that nearly 40 cent of Kiwis are spending fewer than seven hours on the pillow each night – short of the optimal seven to nine hours.

That rate was a worry, as short sleep was consistently linked to problems ranging from psychological distress to poorer sense of health, self-esteem and life satisfaction

Study leader Carol Lee, of the University of Auckland, said poor sleep was common in today's society, yet many of us were unaware of the toll it could take.

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"Multiple studies have shown that insufficient as well as excessive sleep duration can negatively influence our psychological wellbeing in many ways; this includes our subjective health, quality of life and risk of mental illnesses such as depression and anxiety."

With New Zealand's high prevalence of mental health problems, Lee said it was important to better understand those factors at play – especially those which could be changed.

She and colleagues also wanted to unravel ethnic disparities in sleep duration, and whether that could be a driver in poorer mental health among Māori.

They drew upon survey data collected by the New Zealand Attitudes and Values Study, which has been tracking the health and perceptions of more than 15,000 Kiwis.

The researchers asked the participants about how much sleep they were getting each night, together with other questions that made multiple measures of psychological wellbeing.

"Using this data, we were able to examine the unique association between sleep duration and various measures of psychological wellbeing, independent of one's demographic, health and personality characteristics."

The results showed a total 58 per cent were getting optimal sleep, while 37 per cent were getting less than seven hours, and 4.9 per cent were getting more than nine hours.

"The influence of short sleep on psychological health was not so much a surprising finding as many previous studies have noted its negative psychological consequences," Lee said.

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"However, the finding that short sleep continued to show significant associations with psychological wellbeing - even after controlling for a wide range of demographic, health and personality characteristics - does highlight that sleep duration may be a more important contributor to New Zealanders' psychological outcomes than we give it credit for."

On a more positive note, she added, there was the potential for sleep awareness campaigns and interventions to make a difference.

"It is particularly vital to develop target interventions for Māori and Pacific peoples because these groups showed the highest prevalence of short sleepers and are persistently found to exhibit poorer mental health outcomes and lower health care access."