Shutterstock.com Don’t be like this guy. Get more sleep at home in bed. 
 
 How much sleep do you get every night? Studies show that most people try to muddle by on less than seven hours, but new research claims to have found the exact amount of time we need. 
 
 Men need 7.8 hours per night and women need 7.6 hours, according to a study that tracked 3,760 people over seven years and published in the September issue of the journal Sleep. They cross-referenced data on work absence due to illness from Finland’s Social Insurance Institution with sleep disturbances and sickness absence of the study’s participants, who were examined by physicians. After adjusting for age, education, working conditions, health behaviors and mental health, the scientists calculated the “optimal sleep duration.” 
 
 Sleep experts say the results are particularly relevant in the U.S., where 40% of people get less than seven hours of sleep a night, according to a 2013 Gallup poll. Americans, on average, had what’s now regarded as the optimal amount of sleep in the 1940s (7.9 hours per night), but that’s fallen to 6.8 hours in 2013. Americans aged 65 and older report getting the most sleep (67% get 7 or more hours per night) while only 54% of 18- to 29-year-olds and less than half of 18- to 29-year-olds report getting 7 or more hours. 
 
 What college admissions offices won't tell you Five things that the college admissions office won't share with applicants. 
 
 The American Academy of Sleep Medicine recommends between 7 and 9 hours per night, but Nathaniel Watson, president of the American Board of Sleep Medicine, says people are getting less sleep in part because of their increasing reliance on technology. “We generally recommend that people have a period where they wind down before they go to sleep,” he says. “When people are interacting with technology, not only are they interrupting with that wind down period, but they’re being stimulated by blue wavelengths of light, which further makes sleeping difficult.” 
 
 Also see: The high price of insomnia 
 
 What’s more, studies show that people overestimate the amount of time they sleep by around 45 minutes, says James Maas, former chairman of the Department of Psychology at Cornell University who is widely credited with coining the term “power nap”. “Sometimes, you’re going to toss and turn before you fall asleep,” he says. “It’s hard to know accurately the quantity without measuring brainwaves. You can be in bed for eight or nine hours and have a bad sleep.” Bad dreams don’t help, he adds. “Your blood pressure may go up. Nightmares can be exhausting, mentally and physically.” 
 
 This is exactly how much sleep you need Are you getting enough sleep? Scientists reveal the magic sleep number for getting the optimal amount of rest. 
 
 People experiencing sleep insufficiency are more likely to suffer from chronic diseases such as hypertension, diabetes, depression, and obesity, plus cancer, increased mortality, and reduced quality of life, according to the Centers for Disease Control and Prevention. Simon Rego, director of psychology training at Montefiore Medical Center in New York City, says each person has a unique sleep requirement. 
 
 “A simple definition for sufficient sleep is a sleep duration that is followed by a spontaneous awakening and leaves the person feeling refreshed and alert for the day,” he says. 
 
 More from MarketWatch ||||| How much sleep do you really need? 
 
 Experts generally recommend seven to nine hours a night for healthy adults. Sleep scientists say new guidelines are needed to take into account an abundance of recent research in the field and to reflect that Americans are on average sleeping less than they did in the past. 
 
 Several sleep studies have... ||||| Purchase The Current Issue 
 
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 PRINCETON, NJ -- Fifty-nine percent of Americans get seven or more hours of sleep at night, while 40% get less than seven hours. Those figures are largely unchanged from Gallup polls in the 1990s and 2000s, but Americans, on average, slept much more in the 1940s. Americans currently average 6.8 hours of sleep at night, down more than an hour from 1942. 
 
 Medical studies have related a lack of sleep to health problems and cognitive impairment. Therefore, experts typically recommend seven to nine hours sleep for adults. Currently, 59% of U.S. adults meet that standard, but in 1942, 84% did. That means four in 10 Americans get less than the recommended amount of nightly sleep, compared with the 11% who did so 70 years ago. 
 
 Regardless of what the experts recommend and the number of hours of sleep people actually get, 56% of Americans say they get as much sleep as needed, while 43% say they would feel better if they got more sleep. The percentage who say they get sufficient sleep has been in the mid-50% range since 2001, but was much higher in 1990. Gallup did not ask this question in the 1942 poll. 
 
 There is a predictable positive relationship between the hours of sleep one reports getting and that individual's opinion about whether he or she gets enough sleep. Thirty-two percent of those who say they sleep six hours or less say they get as much sleep as needed, which rises to 53% among those getting seven hours of sleep -- the minimum recommendation -- and to 86% among those getting eight hours or more. 
 
 Older Americans Sleep the Most 
 
 Americans aged 65 and older report getting the most sleep, with 67% getting seven or more hours per night. Each younger age group gets less sleep, down to 54% of 18- to 29-year-olds who report getting seven or more hours. Nearly half of 18- to 29-year-olds get less than the recommended amount of sleep. 
 
 Parents of young children and lower-income Americans are two other groups that struggle to get the proper amount of sleep. The difference by income is partially explained by age, as younger Americans are disproportionately in the lower-income category. 
 
 Adults Under Age 50 Most Likely to Feel Sleep Deprived 
 
 Consistent with their lower average of reported hours sleep per night, younger adults are among those most likely to believe they need more sleep than they are getting. Less than half of Americans under age 50 think they get as much sleep as they need, compared with 63% of those between the ages of 50 and 64, and 70% of those aged 65 and older. 
 
 Parents of young children are another group that tends to feel sleep-deprived -- 46% think they get as much sleep as needed. 
 
 Implications 
 
 U.S. adults likely get less sleep than would be ideal, with the average reported 6.8 hours below the minimum recommendation of seven hours per night. Forty percent get six hours sleep or less per night. That is a major shift from 1942, at which time the vast majority of American adults were sleeping seven hours or more per night. 
 
 Even though many Americans sleep less now than they ideally should, the majority, 56%, say they get as much sleep as they need, although this is also down from what Gallup measured in the 1990s. 
 
 Young adults and parents of children under 18 are among the more sleep-deprived groups, while senior citizens tend to be well-rested. Clearly, this is on account of lifestyle, in terms of the demands of working and parenting. Thus, younger Americans who are not getting enough sleep now can look forward to getting more rest as they age and their life situation changes. 
 
 Those changes in sleep patterns throughout the life span could lead to changes in Americans' average sleep in the coming years as the baby boomer generation increasingly reaches retirement age. With baby boomers making up such a large share of the U.S. population, more sleep among this group could push the sleeping averages among all Americans higher in the coming years.
– Suspect you're not getting enough sleep? You can now verify whether that is indeed the case. In a study published last month in the journal Sleep, researchers claim to have determined exactly how much sleep we need: 7.6 hours for women and 7.8 hours for men. The findings arose from a quest to look at the optimal amount of sleep needed to reduce the risk of "sickness absence." To get to those findings, researchers followed 3,760 Finnish participants over a seven-year span and compared their sleep disturbances (such as early morning awakenings and use of sleeping pills) with data on illness-related work absences provided by the country's Social Insurance Institution. They then adjusted for a slew of things, like working conditions and education, and arrived at their figures, noting "direct costs due to sickness absence could decrease by up to 28% if sleep disturbances could be fully addressed." MarketWatch cites a 2013 Gallup poll that found 40% of Americans don't make it to the seven-hour mark; the average amount of sleep was 6.8 hours. That's actually slightly up from the 6.7 hours poll-takers reported to Gallup in 1990 and 2001, but a big drop from how we lived decades ago: In 1942, the average was 7.9. But other recent research suggests the magic amount of sleep might actually be closer to seven hours than eight. Which figure to go with? The CDC might be able to help; it plans to issue new guidelines, possibly as soon as next year. (In other sleep news, find out why you should nap after coffee.)