A group of parents in Ohio, USA, is accusing workers at a day care centre of using medication to get the children to sleep.
The centre at the Covenant Apostolic Church in Springfield Township is now under investigation by police, according to the Cincinnati Enquirer.
Workers allegedly gave kids medication containing melatonin to keep them quiet at nap time.
The drug is a common sleep aid often found in over-the-counter medicines but is usually not recommended for children under the age of 12.
I always wondered how nurseries got all the kids to sleep at nap time... seriously though, this has got to be pretty worrying for the parents involved.
A class-action lawsuit has now been filed against the church by parents Joseph and Andrea Coleman.
Police chief David Heimpold has sent letters out to parents of the 37 children who attend the day care centre.
He tells parents that police do not know which members of staff were involved.
"However, we are providing this information to you at this time so that you can take whatever actions you deem necessary to protect your child or children in the event that they were given melatonin on one or more occasions," he says.
The Cincinnati Enquirer says parents are being urged to contact their family doctors or the Poison Control Centre to find out more about the drug.
Apparently church officials have been cooperating with the investigation, and the day care centre will remain open.
The Rev Shelly Hendricks told the Enquirer that the two staff members believed to be involved were fired when he heard of the situation.
He said: "To my knowledge this is a sleep-aid supplement that can be purchased at any local stores, but this should not have occurred.
"We have fully cooperated with police. Our program remains open and operational and the police are satisfied that our daycare has been run safely."
Source: ParentDish US