Different things seem to work for folks, maybe because of varying cage designs and ambient temperatures. Where I live in the very mild or torrid heat of the So. Cal desert, my indigos only rarely utilize the basking heat provided in winter, a spot light that is in the high 80's about 6 hours a day. Ambient temps here are warm, rarely dropping into the high 50's. I suggest a spot light allowing them to warm up if needed, but mine at least only rarely use it. It could be important at times, such as a large food bolus, gravid condition, ovulation, healing, etc. Most agree providing a range of temps and choices is highly desirable. good luck, Vic