How much sleep do you really need?

Sleep is glorious and many of us feel like we aren’t getting enough of it.

Well, now you have numbers to consult! Just turn to the National Sleep Foundation’s newly released set of recommended sleep duration for various points of life, numbers that were developed after an extensive review of past scientific literature and input from a variety of medical professionals. The recommendations for age categories from newborns to older adults were published in the National Sleep Foundation’s journal Sleep Health.

Here are their recommended sleep times:

• Zero to 3 months of age: 14 to 17 hours.

• 4 to 11 months of age: 12 to 15 hours.

• 1 to 2 years of age: 11 to 14 hours.

• 3 to 5 years of age: 10 to 13 hours.

• 6 to 13 years of age: nine to 11 hours.

• 14 to 17 years of age: eight to 10 hours.

• 18 to 25 years of age: seven to nine hours.

• 26 to 64 years of age: seven to nine hours.

• 65 and older: seven to eight hours.

By comparison, the National Institutes of Health recommends newborns sleep 16 to 18 hours; preschoolers sleep 12 to 12 hours; school-aged children sleep at least 10 hours; teenagers sleep nine to 10 hours; and adults, including the elderly, sleep seven to eight hours.

“Sleeping too little and too much are both associated with increased risk of mortality and a range of other adverse health issues: cardiovascular disease, possibly cancer and also impaired psychological well-being,” said Lauren Hale, editor of the journal Sleep Health and associate professor of preventative medicine at Stony Brook University.

NSF convened an 18-member panel of sleep experts and people representing 12 different professional health organizations, including the American Academy of Pediatrics, American Geriatrics Society and American Psychiatric Association. This panel reviewed 312 peer-reviewed articles published between 2004 and 2014 that dealt with sleep duration and the effects of too little or too much sleep. Panel members met four times over a nine-month period and voted twice to come up with the recommended numbers.

The scope of the results and the methodology behind them make the recommendations a first, Hale said.

“The National Sleep Foundation felt it was the time and their role to assemble this panel, and they’ve been working on it for years,” Hale said. “There has been a shortage of scientific expert panels on the topic of sleep duration. … We just know it’s one of the questions that people ask regularly. People type those questions into Google all the time, and there wasn’t a consensus.”

The foundation had previously posted recommendations on its website, but they were “a bit dated” and weren’t developed following the same kind of thorough literature review and input from various professional organizations as the new guidelines, a spokesperson said. In some cases, the previous recommendations included wider hour ranges or more narrow ones. And new categories were added for younger and older adults.

As for how much people are sleeping: the data is kind of all over the place. You could look to the Bureau of Labor Statistics, which has the average American over 15 sleeping eight hours and 45 minutes. Or, a 2013 Gallup poll in which the average American reported sleeping 6.8 hours nightly.

The Centers for Disease Control and Prevention has called insufficient sleep a public health epidemic. Hale, who focuses on teenagers, said most American teens are simply not sleeping enough on a whole.