>According to Sylvania's Engineering Bulletin 0-362 a 40 Watt lamp can loose >over half of its light output when the bulb temperature increases from >100 degrees F to about 160 degrees F. Correction: According to Sylvania's Engineering Bulletin 0-362 a 40 Watt lamp can loose over one third ( 3000 lumens to 2000 lumens) of its light output when the bulb temperature increases from 100 degrees F to about 160 degrees F.