More than a third of toddlers and a fifth of preschoolers are not be getting the recommended amount of sleep, according to the largest ever study of sleep in early childhood in New Zealand.
The Massey University research - funded through the Ministry of Social Development’s Children and Families Research Fund and carried out in collaboration with the Ministry of Health - examined parent-reported sleep patterns for more than 6000 preschool children in the Growing Up in New Zealand study about sleep duration and quality.
The research compared children’s sleep duration with the Ministry of Health guidelines for preschool sleep - based on the United States National Sleep Foundation guidelines - which state toddlers should get between 11 to 14 hours sleep per day, while preschoolers should get between 10 to 13 hours sleep per day.
The study found that at 24 months, 17 per cent of children involved in the study did not meet the sleep guidelines, with nearly 12 per cent not getting enough sleep while just over five per cent got too much sleep.
It also found that those more likely to experience shorter sleep durations and more night waking included girls, those living in more deprived areas and those living in areas with heavy traffic, as well as Māori, Pacific and Asian children.
At 45 months, it found that nine per cent of children did not meet the sleep guidelines, with just over six per cent getting too little sleep and around three per cent getting too much sleep.
Girls; Māori, Pacific and Asian children; and children who spent more time on visual media were more likely to experience shorter sleep and wake at night, according to the study.
Principal investigator and portfolio director of Fatigue Management and Sleep Health at Massey University’s Sleep/Wake Research Centre, Leigh Signal, said sleep "is vital for children’s healthy growth and development".
"If children are not getting enough sleep it can have implications for their health, including impacts on immune response, body mass, emotional regulation and learning."
She said while it's "natural for children to wake at least once a night" and it’s "a little uncertain whether twice a night is OK", three or more times a night results in consequences for children, including "long term wealth and wellbeing and their risk of becoming overweight and obese"
Researcher and lead author Dr Dee Muller said when the information is statistically modeled for the New Zealand population as a whole, it shows that a third of toddlers and a fifth of preschoolers may not be getting the recommended amount of sleep.
Muller said there was a clear impact on sleep for children living in material hardship or in more deprived areas.
"This may be due to less sleep-conducive environments such as household crowding, or bedrooms that are too cold, noisy or light. These are factors that can be addressed as part of a holistic approach to improving overall living conditions for children in New Zealand."
Signal told TVNZ1's Breakfast this morning that sleep "absolutely is a social issue", adding that there are parents who are working hard to ensure their children are getting enough sleep but “it's about the conditions in which they are living that really make a difference to how well our tamariki can sleep, and so we need to look at that bigger picture to make a difference".
Muller added urban environments were also identified as being less conducive to sleep for many children, likely due to an increase in noise, light and heavy traffic.
She said the research also found an association between poor quality sleep and the use of visual media, such as television and computers, for older preschoolers.
"Greater use of visual media was associated with more night wakings which suggests that visual media may not only reduce the opportunity for sleep but may also disrupt sleep quality, perhaps due to the content viewed.
"We need to continue research in this area to better understand the barriers that are preventing our youngest children getting sufficient, good quality sleep."
Further areas to explore include different sleep patterns between girls and boys and between ethnicities, as well as the factors which influence sleep in childhood, Muller said.
"It is vital that we tackle the root societal causes for why some groups of children in New Zealand are unfairly disadvantaged when it comes to sleep health."