Tiredness can affect your reaction times. See how alert you are with this Adobe Flash game. Test the impact of a cup of tea or coffee on your performance.To play the game, click on the tranquilizer button whenever you see a sheep leaving the flock and running for freedom. There's a 3-second penalty if you shoot a dart when no sheep are running.
http://www.bbc.co.uk/science/humanbody/sleep/sheep/
BBC Sleep Home Page
Link provided by G.R. Welsh.
