Hi @Juliacat and welcome to SF
It’s a necessary evil, I’m afraid.
If it is military pilot operations they must train at night as much as by day and stand ready to defend the Republic. The lower they fly the less likely they are of being detected by enemy radar and counter attack by S2A missiles. Not only that, but the greater the element of surprise to enemy theatre players.
France enjoys an incredibly strong military presence and complaining about night operations will have as much effect as writing to France’s enemies (currently, thankfully, there are no official enemies) asking them to cease all terrorist operations so you can get a good night’s sleep!
As part of NATO they have an obligation to maintain the Alliance and this involves a massive training commitment reference.
You don’t indicate where you are or how close you are to military establshments/training grounds but please be content with the fact that you sleep safe at night because pilots risk their lives training to defend your right to do so.
EDIT: I see in another topic that you perhaps live in the Charente, as do I. IHTS that we are not bothered by night flying operations in our little corner of the Charente in spite of being in an area used regularly by military training aircraft practising aerobatics and close formation flying based at Angoulême-Cognac FlightAware link