if the temperature of your grow room varies i could see the change effecting them, but it depends how big the temp change is. i have a room that ive been using for years thats sort of ventilated but isn't temperature controlled, and i move plants in and out day to day. whenever they gets some sun the leaves always perk up and they grow a few centimeters, but when i move them in at night the temperature is only about 10 degrees higher than outside and i havent ever seen any stress. indica seedlings will like more arid environments and sativea seedlings grow well in a little bit of humidity, and in nature they like to veg in mid summer in about 68-76(not being exact, but id expect the best results around those numbers) degree weather.