Why are you more likely to have a heart attack at 8 o'clock in the morning, or crash your car in the motorway at 2 o'clock in the afternoon. Can taking your medication at the right time of the day really save your life? And why should you encourage your teenager to lie-in in the morning? The answers to these questions lie in the secret world of the biological clock.

Most of us are oblivious to them, but the clocks ticking deep inside our bodies dominate every moment and every day of our lives. We tend to think that we eat and drink whenever we choose, but actually those behaviors are very much influenced by the body clock. This documentary is a journey inside our bodies and into this secret world. Hone through millions of years of evolution, the body clock is your guide to what you really should be doing at any point in the day.

Modern live tends to abuse internal time. We have this exclusive system and we just ride over the top of it and ignore it. Will you choose to listen to your body or suffer the consequences? If you're running your body physiology against its natural cycle, there will be a price to pay according to this documentary.