that light would certainly disrupt ur flowering cycle although a minor dim light shouldn't mess up ur flowering cycle just like moonlight in real nature but a 60w nearby with just a curtain means that the room would still have significant light and flowering will be in trouble + you wana worry about that light shining from behind that curtain if you have someone over and the whole room would smell like weed you can build a good door and wall you can use a gypsum board or wood or just a simple tent if you're not worried about concealing it... cheers