If the light are always off for 6 hours, than this would be normal. The hour before lights on is when your plants will produce the most smell as they start to wake up and get ready for another day of growing. Unlike our kids, plants want to hit the sunlight ready for the day. And ... about an hour or two before lights out, they will start to relax, let thier leaves hang a little to protect themselves from the colder temps they know are coming, so when the lights go out, they are ready to sleep. VV