Bedwetting is not your child's fault, and there's often no obvious reason why it happens. In many cases, bedwetting runs in families.
Sometimes there may be more than one underlying cause.
Drinking lots of fluids in the evening could cause your child to wet the bed during the night, particularly if they have a small bladder.
Drinks containing caffeine, such as cola, tea and coffee, can also increase the urge to wee.
Once the amount of urine in the bladder reaches a certain point, most people wake up as they feel the need to go to the toilet.
But some younger children are particularly deep sleepers and their brain doesn't respond to signals sent from their bladder, so they don't wake up.
In some children, the nerves attached to the bladder may not be fully developed yet, so they don't send a strong enough signal to the brain.
Sometimes a child may wake up during the night with a full bladder but not go to the toilet. This may be because of childhood fears, such as being scared of the dark.
Bedwetting can also be caused by an underlying health condition, such as:
In some cases, bedwetting can be a sign your child is upset or worried. Starting a new school, being bullied, or the arrival of a new baby in the family can be very stressful for a young child.
If your child has started wetting the bed after being dry at night for a while, there may be an emotional issue behind it.