Parents are using potentially dangerous medications to get hyped up kids to sleep at night.
Lucy Shieffelbien, of the National Poisons Centre, said many parents were regularly giving kids antihistamines or paracetamol before bed.
While many of the medications are safe for allergies or as pain relief, they are not intended as sedatives and exceeding the recommended doses could cause serious problems.
She said the practice was more widespread than people realised. "It often comes up as a topic of conversation at seminars and presentations I have given.
"Some antihistamines have sedating properties but should only be given for bonafide reasons such as allergic reaction and not as a pseudo sleeping aid. Parents sometimes use paracetamol as a settling agent if their child is a bit grizzly ... it does not have any sedating properties whatsoever."
She said paracetamol was the number one substance poisoning New Zealand children and can cause liver damage.
Westport mum Jess Moffatt said she had friends who used the antihistamine Phenergan to put their kids to sleep, and they recommended it to her.
"I've had so much trouble getting my 5-year-old to sleep lately but have found that if from about 5pm onwards we keep the house environment really calm, no TV or anything, then give him a hot shower and a few stories, he seems to go to sleep better."
She was not comfortable with the idea of using a drug but said her friends were driven to it out of desperation.
Plunket clinical adviser Allison Jamieson said she knew the practice was common but there was no data available on the prevalence.
"A number of mums in a group might have a problem and try it, and then tell the others to try it."
Plunket advised against it and Jamieson said sleep problems usually needed a plan, not drugs. If parents were worried they should contact their Plunket nurse or GP, she said. "Especially with little people, they need to be aware of what they're using and what it's meant for. With medication, you need to be so careful with little ones."
Sleep consultant Annette Faamausili said it was dangerous because it did not resolve sleep problems and parents could start to rely on it. "It's a very, very slippery slope."