http://www.bbc.co.uk/science/humanbody/sleep/sheep/reaction_version5.swf

do not do as I did and just sit thinking something is going to happen,,,,,
click the button once and when the button changes to a needle get ready to
use it.   Good luck,,, I only have gotten to the second second level on the
first try  but then I did just sit there for awhile.   duhhhh  :-)

Harv