It certainly is. In fact, after being deprived of just one full night’s sleep, people not only have stronger negative emotions the next day, they are much more likely to remember bad experiences than good.
One key study showing the strength of negative emotions after sleep deprivation was conducted by radiologist Seung-Schik Yoo of Brigham and Women’s Hospital and others. Twenty-six healthy young men and women (ages 18 to 30) with no history of psychiatric problems were divided into two groups, one that was deprived of sleep for 35 hours and one that was not. Both groups were then tested in functional magnetic resonance imaging scanners and were shown pictures that ranged from neutral to extremely upsetting, such as images of mutilated animals.
When viewing the upsetting pictures, those who were sleep-deprived showed much more activation of the amygdala, a primitive part of the brain that governs emotional arousal, especially responses to fear. At the same time, the sleep-deprived folks showed less activation of the medial-prefrontal cortex, the front part of the brain that puts a brake on amygdala activity, than the control group.
The reasons for these changes are not known, says Yoo, whose study was published in 2007 in Current Biology, but it’s clear that sleep deprivation is linked to “negative feedback all over the place.” And that may be true even if you don’t miss an entire night’s sleep.
Sleep doesn’t immediately chase away the negativity, according to a 2006 review published in the Annual Review of Psychology. Robert Stickgold, associate professor of psychiatry at Beth Israel Deaconess Medical Center, says data suggest that even after sleep-deprived people get a couple of nights of good sleep, there is still a “horrible bias shift” in their memories of events from the day after their lost sleep.
They “remember twice as much of the bad stuff as the good stuff. If you were living a life of four to five hours’ sleep a night, you might after a while only remember the bad things that happen. If that’s not a route to depression, I don’t know what is.”
Moral of the story: If you want to be happy, don’t skimp on sleep.