Night labor

So I’m 36+5 with my first baby, and I’m getting very excited for her arrival. I’ve lost my mucus plug and I’ve started getting contractions. However, I only get really bad contractions at night. Like clockwork as soon as the sun goes down around 6ish I start getting really really strong contractions that last until about 8 or 9am. I have an app tomorrow so I haven’t had the chance to ask my doctor about them. But any advice as to why I only get them at night? I have some mild ones during the day, but they’re nothing like the ones I get at night, that are usually 7-10 minutes apart. Thanks ladies!