Uncle Billy fell asleep in front of the television again. Five minutes later a noise from the kitchen awakened him. He sat up looking a bit dazed and explained, "I was having something like a dream. I saw my first bicycle, Old Blue, just as bright and shiny as it was when it was new." Uncle Billy was probably experiencing:

1. stage 1 sleep.
2. stage 2 sleep.
3. stage 3 sleep.
4. stage 4 sleep