Humidity at night

Is it ok if the humidity goes up at night when the lights are off? How much of a difference will it make? Trying to save some money and not buy a dihumid

I am having a hard time understandning the way a I should vent at night. Do you just suck the air out of the room when the lights are off? Won't that take all the cO2 out? What is the best way to do it. Oh yeah my lights don't have hoods that I can attach tubbing too.

During the day the room is warm/hot, as it cools (lights off) moisture in the air thickins (humidity). The plant's do not need any co2 at night, they are asleep and most of the moisture that runs from roots to tops has fallen down into bottom stalk/roots. Plant is shut down.
I use my simple Laundry room exhaust fan, or if it gets above 60 at any time I set a fan in door to pull out and push away air in room.

Do a search on my posts. I started a thread called something like did it rain in my grow box. I have a picture of a plant in that thread and it looks like it got rained on. All caused by not running the exhaust fan all night. My grow cabnet acted like a humidity dome that you would use for clones. I have a bathroom exhaust fan at the top of the cabnet and 3-3" holes in the bottom back for air intake. The fan creates negative pressure in the box so no smell leaks out and it goes through the exhaust fan and carbon filter.

what is the easiest way to run an exhaust in my room?