The Zoo Med brand red bulb is a good way to provide heat to your tortoises at night. While other brighter sources of light are turned off, the red color of this light will not interrupt the sleep patterns of reptiles, so you can continue seeing them without them being kept up by the other light sources. These can be used on a dimmer or a timer. We commonly leave them on 24/7 to heat the enclosure day and night, and just turn off the strip and spot lights at night. These also are great for use in outdoor hideboxes on cooler nights and during winter.