No need to vent at night?

I've read that you need not vent at night. Is this ture? Don't plants still respire at night and therefore need oxygen?

I ask this because I have high RH and my only real option for controlling it would be to run a dehumidifier at night and not vent (or maybe vent a lot less). I have an RVK100 venting a tiny grow tent and I don't think any dehumidifier I can fit in there will have much impact when it's on.

c'mon folks help a fellow grower out!

yes plants cycle changes at night the breath in O and breath out co2 so fresh air is key