A prefatory disclaimer, I only have Borneo STPs not red bloods, but if I did I would keep them the same way. Over at VPI.com they mentioned they kept theirs in a room with ambient temperatures between 78 and 82 degrees, with no supplemental heat. I took a page from their experience after noticing that 99% of the time mine was on the cool side. I can't provide a room that meets those conditions, so I have greater variance, but the cool side stays at 78 to 79 degrees, day and night. The basking spot pretty much never exceeds 86, and tends to stay closer to 84. The ambient temperature wavers in the low 80s. I have not had any problems with this arrangement, digestion occurs normally and defaction equally normally (ie, rarely.) In Kalimantan (Indonesian Borneo) the temperature range is between about the low 70s on one extreme and the very low 90s on the other. At the upper end of this scale I would be very surprised to see any STPs active...as more likely they would be resting on the comparatively cooler ground, most likely adjacent a water source, out of direct light. in fact, the one time my female STPs cage temps broke 90 (thermostat malfunction...different story) she raced around constantly, in great distress. Just my limited experience.