The secret life of your body clock.

This documentary looks at the secret world of our biological clocks. Areas covered include why it is so hard for teenagers to get out of bed in the morning - between the ages of 13 and 21 all people sleep later into the morning than at any other time in their lives. One headmaster is rethinking the structure of the timetable in his school in order to accommodate the teenagers' most attentive times of the day. Between 6am-12pm our blood pressure is at its highest, thus making this the most common time a heart attacks occurs. Mid-afternoon urges to sleep are not to do with food but more to do with the time of day when our body clocks tell us we need a micro sleep. The central body clock lies deep within the brain but every individual organ also has a body clock - this can be exploited when using drugs to kill disease within the body. Chemotherapy medications, for instance, can be given at a time in which the body's own defense system is at its lowest so fewer good blood cells are killed by the drug. Exercise is best taken between 4-6pm, the time at which most athletic records have been broken. Drinking alcohol at lunchtime will make one sleepy while at 7-9pm it has the least potent effect. Eating the main meal of the day in the evening is not natural for our bodyclock, most calories are meant to be consumed at breakfast or lunchtime. The time one feels ready for bed is individually variable, but light can be used to adjust our natural sleep patterns. Night shift workers are prone to more serious illness than day workers although more babies are born between 3-5am.