You

and your body

What happens in your body at night?

Finding out what's happening inside your body might help you to understand why you wet the bed and make you feel a little better.

Urine is made in your kidneys and stored in your bladder until you go to the loo and let it come out.

Your kidneys make urine out of things that your body doesn't need anymore like food and drink. At nighttime your body produces something called a "hormone" that tells your kidneys to slow down and stop making so much urine. Some kids don't make enough of this hormone and their kidneys keep on making urine. That's one of the reasons some kids wet the bed sometimes.

After the urine leaves your kidneys, it goes down into a round organ called the bladder. This is made out of muscle fibres that stretch like a balloon. But some kids' bladders aren't big enough yet. Even when it stretches, it hasn't grown enough to hold urine all the way through the night. That's another reason some kids wet the bed.

There is a ring-shaped muscle called a sphincter (which is pronounced "ss-FINK-ter") at the bottom of your bladder. When it's closed, it holds the urine in the bladder; when it opens up, the urine flows out. In some kids, this muscle is too weak to stay closed and hold in the urine, so the urine comes out when they don't want it to, especially at night.