Some 15,000 children across the country, and a few dozen office workers, are wearing their pyjamas all day today in a bid to raise €150,000 for sick kids.
As part of efforts to raise cash for the Make-A-Wish Foundation, more than 400 childcare centres, schools and nurseries will have thousands of youngsters donning bed clothes.
A handful of workers in Dublin have also promised to dress down for the day at work.
A spokeswoman for Make-A-Wish said it was important children helped to raise money for kids their own age with life-threatening illnesses.
“The knock-on effect has been amazing with even a number of offices taking part. It seems to be going from strength to strength,” she said.
The National Children’s Nursery Association, which helps organise the pyjama day, hopes to raise €150,000 for Make-A-Wish.
The money will help grant more than 20 wishes to help a sick child forget about their illness for a while.