not harsh at all, i'd rather have happy snakes, then cold-hot or DEAD, im not cheap but i do try to save some, i bought a zoomed dimmer when i first got my bp, and it sucked, so i switched to a nomral dimmer but my snakes are at my girl friends house and she know all about them, but we both go to collage, so its hectic to always, check the temp, and i wanted somthing more concrete, that i don't have to adjust every hour