After all, do we need 8 hours of sleep a night?

It's the holy grail of questions: How many hours of sleep per night would be ideal? For this question, most people's answer is instant - 8. But experts are working to come up with a number based on more concrete evidence.

How many hours of sleep do you really need?

Some professionals generally recommend 7 to 9 hours a night for healthy adults. Sleep scientists say new guidelines are needed and a lot of recent research should be taken into account.

Several studies have found that sleeping 7 hours is the ideal amount of sleep - not 8, as has long been accepted - given certain cognitive and health markers, although many doctors question this conclusion.

Other recent research has shown that reducing the amount of sleep needed, even for 20 minutes before completing the cycle, impairs performance and memory the next day. On the other hand, its excess is associated with health problems, including diabetes, obesity and cardiovascular diseases with high mortality rates.

"The lowest mortality and morbidity is seven hours of sleep, " said Shawn Youngstedt, a professor at Arizona State University's College of Nursing and Health Innovation in Phoenix. "Eight hours or more has consistently been shown to be dangerous, " he says, which researches the effects of oversleeping.

The Centers for Disease Control and Prevention is helping to fund a panel (meeting of professionals for debate and research definition) of medical specialists and researchers for a review of the scientific literature on sleep and the development of new recommendations. The expectation is that the works begin in 2015.

Daniel F. Kripke, emeritus professor of psychiatry at the University of California, San Diego, tracked data over a six-year period from 1.1 million people who participated in a large cancer study. People who reported sleeping 6.5 to 7.4 hours had a lower mortality rate than those with shorter or longer sleep. The study was published in Archives of General Psychiatry in 2002, taking into account 32 health factors, including effects of medication use.

In another study, published in the journal Sleep Medicine in 2011, Dr. Kripke found more evidence that the ideal amount of sleep may be less than traditional eight hours. The researchers recorded the sleep activity of about 450 elderly women who used a measuring device on their wrists for a week.

About 10 years later, researchers found that those who slept less than 5 hours or more than 6.5 hours had a higher mortality rate.
Other experts dispute studies that show harmful effects of excess sleep. An illness could cause drowsiness or make the person spend more time in bed, they say. That is, it would exchange the effect for the cause. In addition, studies based on people's reports of their own sleep patterns are inaccurate.

"The problem with these studies is that they give you good information about the association, but not the cause, " said Timothy Morgenthaler, president of the American Academy of Sleep Medicine, who represents sleep doctors and researchers and professor of medicine. Mayo Clinic Center for Sleep Medicine.

Another expert, dr. Morgenthaler advises patients to sleep 7 to 8 hours a night and self-assess, describing how they feel. Sleep needs also vary among individuals, largely due to cultural and genetic differences, he said.

Is seven the ideal number?

Getting the right amount of sleep is important to be alert the next day, and several recent studies have found an association between seven hours of sleep and optimal cognitive performance.

A study published in Frontiers in Humans Neuroscience magazine last year used data from users of the Lumosity cognitive training site. The researchers analyzed the sleep habits reported by the approximately 160, 000 participants who took spatial and correspondence memory tests. In addition to them, about 127, 000 users also take an arithmetic test. They found that cognitive performance increased as people slept more until they peaked at seven hours before it began to decline.

After seven hours, “increasing sleep was no longer beneficial, ” said Murali Doraiswamy, professor and psychiatrist at Duke Medical Center and University in Durham, North Carolina. He is co-author of the study with scientists at Lumos Labs Inc., owner of the Lumosity website. Doraiswamy said the study replicates previous research, including a result linked to lack of sleep and memory loss. "If you think of all the causes of memory loss, sleep is probably one of the most influential factors, " he said.

Most research has focused on the effects related to a few hours of sleep, including cognitive impact, health loss and weight gain. David Dinges, a sleep scientist at the University of Perelman School of Medicine, Pennsylvania, who studied sleep deprivation, emphasizes that if we stay (only) 20 or 30 minutes less than the minimum recommendation of seven hours, this can be slow cognitive speed and increase attention lapses.

Experts say people should be able to find out their ideal amount of sleep on a three day to a week test, which should preferably be performed during the holidays.

Do not use an alarm clock. Go to sleep when you get tired. Avoid too much caffeine or alcohol - and stay away from electronic devices such as smartphones and tablets a few hours before going to bed. During the test, make notes in a sleep quality journal or use a device that records the actual time you have been sleeping. If you feel refreshed and wide awake during the day, you have probably found your ideal sleep time.

The new sleep guidelines will be prepared by a panel of experts being assembled by the American Academy of Sleep Medicine, the Sleep Research Society, a sleep research organization, and the CDC. The recommendations are intended to reflect evidence that emerges from scientific studies and should take into account issues such as gender and age, says Dr. Morgenthaler, president of the Academy.

The National Sleep Foundation, a nonprofit research and advocacy group, has also set up a panel of experts that hopes to make updated recommendations for sleep time, estimated to begin in January 2015.

These groups currently recommend 7 to 9 hours of sleep per night for healthy adults. The National Heart, Lung and Blood Institute recommends 7 to 8 hours, including the elderly group. Most current guidelines say that school-age children should get at least 10 hours of sleep a night, and teens, 9 to 10.

"I don't think you can overdo your healthy sleep. When you get enough sleep, your body will wake you up, " said Safwan Badr, head of the pulmonary health, intensive care and sleep medicine division at Wayne State University School of Medicine in Detroit.

Technician and Mining

Back to the origins

A study published in the current issue of the Journal of Clinical Sleep Medicine seemed to confirm this. Five healthy adults were placed in isolation in what the researchers called the "stone age" in Germany for more than two months. They were deprived of electricity, watches and even running water. Participants slept about two hours earlier and were on average 1.5 hours more sleep than estimated (by them) in their normal lives, according to the study. The total hours they slept?

Their average amount of sleep per night was 7.2 hours.

And you dear reader? Do you agree with the studies and think we sleep too much? Do you feel good when you wake up for the time you sleep? Comment below.