It's time for people to wake up and realise they need sleep.
Fifty five per cent of Kiwis say they never wake refreshed, and trying to fix the problem - swapping sleep for work or exercise, drinking alcohol to "relax", using a cellphone or computer screen at bedtime - can lead to premature ageing, serious health problems and early death.
Sleep disorders, including night terrors, sleepwalking and restlessness, also affect children, setting up patterns that could dog them all their lives.
Dr Alex Bartle, founder of the Sleep Well Clinic, said sleep disorders were often traced to childhood where, for whatever reason, a child learned to never relax into deep sleep.
Adult women and men should sleep six to eight hours a night; some people needed more.
Bartle holds monthly clinics in Whangarei, and talked to the Advocate before today's World Sleep Day.
"Hugely prevalent" sleep disorders were behind many cases of depression, and caused short-term memory, concentration and stamina loss.
Treatments did not have to involve medication but sometimes did, at least in the interim.
"About 30 per cent of anything you put in your mouth is going to immediately make you sleep better because of the placebo effect but it doesn't last. The best long-term treatment is to change sleep behaviour."
Overnight studies of Bartle's clients' involve them plugging themselves into an oximetry machine that arrives and is returned by courier. It measures oxygen levels and how often a client stops breathing.
Apnoea causes disturbed sleep in 25 per cent of adults; other common reasons include snoring, insomnia and restless sleep syndrome.
Snoring can be a symptom of the more serious sleep apnoea, where pauses in breathing while asleep deprive the body of oxygen, and is linked to cardiovascular disease, obesity, diabetes and cancer.
Less sinister causes of bad sleep include Northland's high summer night temperatures and humidity (a fan not only cools the room, the background "white" noise can also aid sleep, Bartle recommends).
If you're anxious and tense for a particular reason, you might have to accept a period of poor sleep. But if you're generally anxious and never sleep well, your sleep behaviour needs changing, he said.