I used a red bulb for a good while and had no issue. Eventually my snake started getting super stressed and lying outside the hide, not eating, and moving during the day. I ended up changing to a regular Ceramic Heat Emitting bulb, and the issues stopped. To be fair I also moved the hides around and hung a few vines from the roof of the viv, so don't know which thing was key, but after it all I never had another issue