In March 2009 BBC's Horizon aired The secret life of your body clock.
Why are you more likely to have a heart attack at eight o'clock in the morning or crash your car on the motorway at two o'clock in the afternoon? Can taking your medication at the right time of day really save your life? And have you ever wondered why teenagers will not get out of bed in the morning? The answers to these questions lie in the secret world of the biological clock.
You can read the transcript for the first thirteen minutes of the programme here.