Everyone has heard of the biological clock. What is it? How does it work?

The biological clock is a mechanism deep inside the brain that regulates wakefulness. This is known as "clock-dependent alerting".

Students encounter the biological clock, often after lunch. They can be desperately tired in the mid-afternoon. Many think that it is the lunch that they ate, that makes them tired. But after dinner, they won't be tired. Why doesn't the food at dinner make them as tired as the food they ate for lunch? Clock-dependent alerting is what creates these effects. The amount of sleep debt that a person is carrying can also be a factor in how strong this effect is.

For young people, the strongest alerting affect is late in the day. Older people tend to be stimulated earlier in the day.

The biological clock keeps us awake during the day. All wakrefulness is sleep deprivation!

Other interesting resources:

Clocks, watches, biological clock, natural rhythms