Are you the kind of person who sometimes stays up late to do some work, or do you prefer to get up early in the morning to finish it? Your body clock helps to decide what you prefer. Research has shown that everybody has an internal body clock that influences their behavior at different times of the day. Our body clock makes sure that we are sleepy at night but not during the day, and hungry at mealtimes but not during the night. It even controls how active we feel.

Our habits are important too. For example, if you go to sleep at the same time each night, it can be quite difficult to change this. Our bedtime, however, is not only a question of habit. Our own body clock is important too.

Experiments with people who are put into dark caves without clocks or watches have shown that body clocks run on a twenty-five-hour day instead the usual twenty-four-hour one. Daylight, night and mealtimes cause our body clocks to follow the twenty-four-hour clock. Usually this works well, but some people’s clocks do not follow the twenty-four-hour cycle.

Some people are like owls, birds that are active at night; others are like larks, birds that are active in the morning. ‘Owls’ like to stay up late at night, but find it very difficult to get up in time for work or school. ‘Larks’ prefer to go to bed early and start their day before other people usually get up.

‘Owls’ are not lazy – they have a slow body clock that runs on a twenty-five-hour cycle, so they always need more time in the morning. ‘Larks’ have fast clock – they have no problem getting up, but they are ready for sleep before most people.

Don’t blame your body clock if you are continually late for school or work though! Everyone can learn to follow school or work time, but some body clocks make it more difficult than others.