Why Sleeping 6 Hours Is Just as Bad as Pulling an All-Nighter

March 16th 2016

Laura Donovan

A 2003 study in the journal Sleep found that getting six hours of sleep can have similar effects as not sleeping at all. So, if you are an adult who doesn't get the recommended seven to nine hours of rest every night, then you might be in bigger trouble than you may have initially thought.

The study, which was conducted by University of Pennsylvania researchers, looked at 48 healthy adults ages 21 to 28 and placed them into three separate groups given a certain amount of hours to sleep. One group slept four hours, another slept for six hours, and the final group slept for eight hours for two weeks straight. The study also required people to go three nights without sleep at some point in the experiment. For every two hours that each group was awake, researchers tested participants’ cognitive performance and reaction time.

Those who slept four hours a night had worse results each day, but the academics also found that people who slept six hours a night had a similar performance level to those who hadn't slept for two days straight.


"Since chronic restriction of sleep to six [hours] or less per night produced cognitive performance deficits equivalent to up to two nights of total sleep deprivation, it appears that even relatively moderate sleep restriction can seriously impair waking neurobehavioral functions in healthy adults," according to the study.

The study also noted that people who slept six hours didn't realize how tired they were despite their poor test results.

"Sleepiness ratings suggest that subjects were largely unaware of these increasing cognitive deficits, which may explain why the impact of chronic sleep restriction on waking cognitive functions is often assumed to be benign," the study authors wrote.

The potential consequences of getting too little sleep.


While the study sample in this particular paper was small, it's no secret that sleep deprivation is bad news. The National Sleep Foundation recommends getting seven to nine hours of sleep per night for adults under 65, but a 2013 Gallup study found that 40 percent of Americans get less than seven hours of rest per night. Research has shown that poor sleep quality can lead to a host of health issues, including heart disease, depression, obesity, and diabetes, among others.

Earlier this year, a study published in Diabetes Care found that poor sleep can increase one's risk of developing diabetes, especially for people with hectic schedules who overeat to stay awake.

"This could mean consuming sugar or other foods that can spike blood sugar levels,“ Dr. Lynn Maarouf, who works at the Stark Diabetes Center at the University of Texas Medical Branch in Galveston, said in a recent interview with WebMD. “I really push people to eat properly throughout the day and get their blood sugars under control so they sleep better at night. If you get your blood sugar under control, you will get a good night sleep and wake up feeling fabulous with lots of energy.”

A lack of sleep can also bring on irritability, which can in turn cause tension at the workplace. It doesn't end with hurt feelings or awkwardness, either. A 2011 study from Harvard Medical School found that the economy loses $63 billion annually from poor performance caused by insomnia.

RELATED: The Real Reason People Talk in Their Sleep