how body can recognize biological clock?

Answer 1

That's a very interesting question. Some completely blind people can't tell night from day because they don't receive V-d from sunlight ans a seeing person would. Sometimes they are given Melatonin Vit. D to regulate their sleep cycle.

Answer 2

There was an interesting study in france where they actually discovered that humans have a 25 hour biological clock in their head. They put a man in a cave and gave him everything he needed to survive except actual sunlight. He went to sleep at the same time every day, but it would switch by one hour each time. So since we normally use a 24 hour clock this proves that some people don't get enough sleep.

Answer 3

You are asking about the circadian cycle which tells our body to wake up and to go to sleep. This biological cycle resets every 25 hours and dictates peak body temp, pulse rate, and blood pressure (1600 hours) as well as several different factors.