What could cause a five year old to start wetting herself at night?

One of my five year old twins girls has started wetting herself again at night. She hasn't had a wet night in three and a half years.She has no liquids before bed and we make sure they both go to the toilet before bed. She's wet herself in her sleep every night for the past two weeks, in the past she's woken up to go to the toilet in the night when she has needed to, now she does not. What could have caused her to start wetting herself at night?

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia…).