By Greg Argos

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PHILADELPHIA (CBS) —  A good night’s sleep means something different to almost everyone. “I want to get ten hours, but six is usually what I get,” said one person. “Seven hours,” another person said.

But what’s almost universal is how getting too few Zs impacts most people.

A new study from Sleep Researchers at Iowa State University confirms what most people already figured out: getting too little sleep makes you more irritated and angry.

The researchers took 142 participants, randomly split them in half and asked one group to sleep only 4-5 hours a night.

Those folks who were sleep deprived became more irritated more quickly at different distractions.

Surprisingly, this is the first study of its kind.

Marc Johnson is the clinical director at Drexel University’s sleep center and says someone who is tired simply has less of the ability to concentrate and that affects mood.

“You’re more able to process more information clearly. If you’re sleep deprived, you’re not able to do the normal daily tasks,” said Johnson.

He also points out Americans, in general, are more sleep deprived and he blames odd work hours, light from electronics, even this time of year for the trouble at night.

“Between November and January, people are not sleeping well because they’re stressed out by the holidays,” says Johnson.

So, take a deep breath, turn off that iPhone and try to get a good night’s rest.