Having an overactive bladder can cause you to wet the bed since your bladder is overproducing urine and filling up your bladder with too much urine in too short of a time and not allowing you to get to the restroom.
If you're wetting the bed you might want to see your doctor who can prescribe some medication to help with your overactive bladder.
And you might want to wear some adult pull ups or adult disposable diapers to keep your bed from getting wet and ruining your mattress.