Medical experts say New Zealand must improve the diagnosis and treatment of a common sleep-related breathing disorder.
The call follows an article published in the Medical Journal on Friday estimating that untreated Obstructive Sleep Apnoea is costing at least $40 million a year.
Obstructive Sleep Apnoea is characterised by repetitive episodes of restricted airflow and breathing, accompanied by snoring at night and excessive daytime sleepiness.
It is estimated to affect 2 - 4% of middle-aged New Zealanders.
Sleep researchers writing in the Medical Journal say adults with undiagnosed sleep apnoea are high users of health services, and medical costs, motor vehicle accidents and lost productivity all contribute to high costs overall to society.
Auckland specialist Dr Andy Veale says nodding off momentarily while driving is a common symptom.
Jeff Garrett, a respiratory physician at Middlemore Hospital in Auckland, says a national strategy is needed to deal with the disorder.