Ya the temp is going to go up abit, you could run out to home depot or walmart and grab a dimmer and hook the light up to that so you can control the temp, they cost inbetween 8 to 15 bucks for the kind you would be able to use. You could do this till you can get your hands on thermostat or you could just get the thermostat right away. I recommended the dimmer first because I don't know your financial situation and some of the better thermostats can be kind of expensive unless your good with web sites like ebay and stuff then you can find some good deals on some of the good ones.