There's no set age that a child should stop wearing diapers to bed at night if they need them.
Some kids may be dry and stop wetting the bed by age 4 or 5 years old and some kids may continue to wet the bed until age 7 and as late as age 17 or 18.
If the child wets the bed at night then they should wear diapers to keep their bed dry and their clothes dry.
Believe me I wish I had diapers to wear when I was a kid and wetting the bed but my parents never put me in diapers for bed wetting and I suffered through having a wet bed and wet clothes.
Diapers are embarrassing for some people and not the best thing to wear for people but it sure would be better than having a soaking wet bed and soaking wet clothes.
It's an awful feeling waking up in a cold wet bed and clothes and a diaper would be a better option.
I wet the bed until I was 17 years old and it was miserable and when I had money I would buy adult diapers to wear on my own and it made me more comfortable.
My kids who are 7 and 10 years old wet the bed and they wear diapers for the bed wetting and there's nothing wrong with that.
Diapers are for all ages and they are great thing to wear to keep your clothes and bed dry.