My daughter (5) sees a urologist for some muscle development issues. Her urologist said she does not worry about night wetting in kids until they are well into school, around 8 years/second grade. The bladder system isnt fully developed until somewhere around 7 years old. If she was previously dry and is no longer, they need to be sure there are no physical issues like some reflux or bladder infections. If everything is fine physically and she was previously dry at night, it is likely psychological. If she has never been dry, or not for long extended periods of time, it is likely still developmental. Be sure to check with the pedi for physical issues.
Hi, about 12% of kids all the way up to age 9 wet at night. It is a common problem and believe it or not, most kids that wet into the later years had parents that did!
Kids that do this are often heavy sleepers or don't fully get the signal yet to wake out of a sleep to get up and go to the bathroom. They typically mature into it naturally as time goes on. I think what you can do to help in the mean time is to decrease fluid intake before bed. Be sure to have them go to the bathroom prior to getting in bed so their bladder is totally empty starting the night off. Going to the bathroom can be a habit, so some will also try getting up at say 3 am and walking thier child to the bathroom and having them go. Do it for a week and the child may start to do it on their own.
good luck to your friends daughter