Temperature range at night?

Hey guys, so i moved my seedlings to my 400w for the first time, into my new closet for the first time. When I left it on for a few hours, temperature was 78 degrees which is pretty sexy I think. Now when i woke up in the morning to turn the lights on the temperature was 57 degrees, pretty unsexy I think.

Will temperature drops like that be a big problem? Note the closet door was open all night as I am still setting it up (fan not installed yet, etc.)

well usually the plants like no more then a 10degree difference between night and day but...i think u should be ok...why so cold in your house, are you trying to hatch penguin egg's in their, turn your heat up brother...or you can spend 20 30$ at a stor and get a little electric space heater...easy fix

It's in a cold basement. Would an electric blanket be okay for underneath the thing?

yeah i think it would but u might have to do a lil experiment to see just how hot it gets the soil, you dont want it to hot....so try it out on a empy pot..make sure the soil is wet to like you plant...