There are photo studies being done on light UV and health with crepuscular snakes the preliminary results are absolutely pointing to the need of such lights. This is calling into light the possibility that the royals twilight activity may serve other purpose other than thermoregulation this is no more than a theory at this point. There is no direct studies being done on nocturnal snakes. The eye structure has be dissected and understood for ages as have the labial pits.