Have you ever woken up after 8 hours of sleep and thought to yourself that you could sleep for a few more? Perhaps something from your evolutionary past is calling to you. A new study suggests human sleep is more efficient than that of other mammals because we have evolved to sleep for fewer hours, in deeper sleep stages.The study, published in the journal Evolutionary Anthropology, examines sleep patterns across hundreds of mammals, and humans.

According to them, how much sleep we need as individuals varies, but it changes as we age. For example, school-age children need about 10 hours of sleep each day, while teenagers need 9-10.

Adults need around 7-8 hours of sleep a day, but according to data from the National Health Interview Survey, almost 30% of adults sleep a reported average of less than 6 hours of sleep each night.

The team found that humans are the shortest sleepers - slumbering for an average of 7 hours each night - while other species of primate, such as the southern pig-tailed macaques and gray mouse lemurs, need 14-17 hours.

The researchers found that our sleep is more efficient. We spend nearly 25% of our overall sleep in rapid eye movement (REM) sleep - which is a deeper stage of sleep - whereas other primates spend only 5% of their time in this sleep state.

In our modern world of artificial lights and gadgets with screens, it would be easy to blame technology for our shift in sleeping patterns, but the team says this is not the culprit.

A completely different study into sleeping habits of hunter-gatherer societies without electricity in Tanzania, Namibia and Bolivia concluded that they actually get less sleep than those of us in a tech-obsessed society.

So, if modern life were to blame for our shortened sleep, these hunter-gatherer societies that do not have access to electricity would presumably sleep more.

The researchers add that less sleep would give early humans longer periods of activeness, during which they could acquire new skills and knowledge. Meanwhile, deeper sleep is necessary to consolidate these skills and leads to "enhanced cognitive abilities."

So all said and done its not how LONG u sleep,but its how DEEP you sleep that matters more. Now that you know the truth ,search for your own ways and means to sleep deep,than slipping into bed for more hours...Happy sleeping!!!

--pushpa