New York, March 16 : You must have heard one should sleep for eight hours, but researchers say that it depends on a person's genetics. When it comes to sleep, quality matters over quantity. People with Familial Natural Short Sleep (FNSS) prefer to sleep just four to six hours a night, and yet have the ability to function fully on. According to researchers at University of California, San Francisco, these "elite sleepers" show psychological resilience and resistance to neurodegenerative conditions that may point the way to fending off neurological disease. It means that the brain accomplishes its sleep tasks in a shorter time. In other words, less time spent efficiently sleeping may not equate to a lack of sleep, said Ying-Hui Fu, from the UCSF Weill Institute for Neurosciences. The researchers have shown that it runs in families and, thus far, have identified five genes across the genome that play a role in enabling this efficient sleep. "There's a dogma in the field that everyone needs eight hours of sleep, but our work to date confirms that the amount of sleep people need differs based on genetics," said neurologist Louis Ptacek, from the Institute. In the study, published in the journal iScience, the team chose to look at mouse models of Alzheimer's disease because that condition is so prevalent. They bred mice that had both short-sleep genes and genes that predisposed them to Alzheimer's and found that their brains developed much less of the hallmark aggregates associated with dementia. To confirm their findings, they repeated the experiment using mice with a different short-sleep gene and another dementia gene and saw similar results. The team believe that similar investigations of other brain conditions would show the efficient-sleep genes confer comparable protections. improving peoples' sleep could delay progression of disease across a whole spectrum of conditions, they said. "Sleep problems are common in all diseases of the brain," Ptacek said. "This makes sense because sleep is a complex activity. Many parts of your brain have to work together for you to fall asleep and to wake up. When these parts of the brain are damaged, it makes it harder to sleep or get quality sleep." Understanding the biological underpinnings of sleep regulation could identify drugs that will help ward off problems with sleep disorders. In addition, improving sleep in healthy people may sustain wellbeing and improve the quality of time we each have, the researchers said. /IANS