Vaginal itchiness at night instead of during the day can be attributed to the following reasons: 1. vaginal pinworms, a specific inflammatory disease of the vagina, which occurs mainly in young girls, and the itchiness usually occurs mainly at night and is rarely felt during the day. 2. allergic reactions, some women have allergic reactions to condoms used during sex or to male semen. The first thing you need to do is to have an allergic reaction to the condom used during sex or to male semen.