How much Sleep does a person need daily to stay healthy? I'm sure your answer would be eight hours, but according to the latest scientific research, this is not entirely true.

Louis Tachek, a professor of neurology at the University of California, USA, told the BBC: "It's a misconception. It's like saying everyone should be 1.65 meters tall and if you're shorter then there's a problem

Not all of us need the same amount of sleep to feel refreshed and function throughout the day. And it's not a matter of behavior or personal choice, it has to do with genetics. Some people are genetically made up to naturally sleep less. This means that even after sleeping only four to six hours every night, they Wake up completely refreshed

"These are the people we call 'elite sleepers,' and I think that's understandable," says Dr. Tatchek. They perform their tasks vigorously even with very little sleep. And it is true that this is an advantage in the world we live in.

For the past 25 years, Dr. Tatchek and his team have studied the sleeping patterns of more than 100 families.

"Initially, our work was focused on what the criteria should be for someone to be called a 'deep sleeper'."

People who go to sleep early at night and wake up early are called sleepy. These were the people who attracted us. These people were very charming, but they slept very late by our standards.

So Dr. Tatchek learned that there are families who sleep late at night but wake up early in the morning.

A team from the Department of Neurology at the University of California found that people who sleep fewer hours actually have a different condition.

These are sleepers who have a 'naturally short sleep' which makes them wake up early even after going to bed late.

So far, four genes have been linked to naturally short sleep, but there may be more.

The challenge is that these genes are very rare. Dr. Tatchek estimates that one in 1,000 people are such 'elite sleepers'.