S/I: Sleep Crossword Puzzle

12345678
Across
  1. 6. slowly respond to light and slowly turn off when light is absent
  2. 7. rotates about every 24 hours
  3. 8. the pineal gland secrets this hormone to increase sleepiness
Down
  1. 1. a rhythm that occurs when no stimuli rest or alter the rhythm
  2. 2. region of the brain that serves as the biological clock, that maintains circadian rhythms to a 24 hr period
  3. 3. a stimulus that resets the circadian rhythm
  4. 4. input comes from a special population of retinal ganglion cells that have their own photopigment
  5. 5. neurons in the SCN are very active during the _______