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Body + BrainBody & Brain

Poor-quality sleep could prime the brain for an anxious day

From a neurobiology perspective, anxiety and sleep deprivation look very much alike.

ByKatherine J. WuNOVA NextNOVA Next
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Sleeplessness isn't just a symptom of anxiety—it can be a root cause, too. Image Credit: Milkos, iStock

If your anxious brain is keeping you up at night, Eti Ben Simon has some not-so-great-news: The sleep you lose to stress might exact an additional emotional toll on your wellbeing the next day.

“Typically, people think of lost sleep as a symptom of anxiety,” says the University of California, Berkeley neuroscientist. “But disturbed sleep can be an instigator of anxiety, too.”

Ben Simon and her colleagues have spent years studying the relationship between sleep deprivation and anxiety—two experiences that, from a neurobiological perspective, actually look pretty similar. The team’s latest findings, published today in the journal Nature Human Behavior, show that both affect brain regions that regulate emotions.

Functionally, that means experiencing one can aggravate the other, fueling a cycle of stress and sleeplessness. It’s pretty much a two-way street, Ben Simon says. And it doesn’t take much to trip the system: Enduring even one session of low-quality shut-eye, the study suggests, can boost anxiety the next day.

But there’s a flip side to the findings, too. A good night’s sleep, Ben Simon says, could be a straightforward way to manage our emotions. With more research, she says, sleep therapy could someday offer an additional treatment option for those that struggle with chronic anxiety.

“This is a very elegant study,” says Bunmi Olatunji, an expert in anxiety disorders at Vanderbilt University who was not involved in the study. “They really went after the biological underpinnings of the relationship between sleep and anxiety, and that’s an important and unique contribution.”

Researchers have long been aware that low-quality sleep is intertwined with a number of mental health conditions. People with anxiety disorders frequently have trouble falling and staying asleep, and insomnia can exacerbate the symptoms of clinical anxiety. It’s an especially troubling connection, Ben Simon says, in a world where younger generations are staying up late and feeling more stressed out than ever.

But no one’s managed to compare the two experiences in a systematic way, she says, especially in the same individual. “We wanted to know if there was a shared neurobiological mechanism,” she explains.

To explore the link between the two conditions, Ben Simon and her colleagues recruited 18 healthy people for two overnight sessions: one where they were sent home for a normal night of rest, and another where they stayed at the lab and didn’t sleep at all. Before bedtime, the researchers scored the participants’ anxiety with a questionnaire. When they repeated the assessment the next morning, they found that a total lack of sleep triggered a 30% increase in anxiety levels.

To home in on the brain regions responsible for the uptick in stress, the researchers put the study subjects in a functional magnetic resonance imaging (fMRI) machine, which monitors blood flow as a proxy for brain activity, after each session. During the scan, participants watched a series of video clips, some of which featured distressing situations.

Compared to when they were well rested, sleep-deprived participants seemed to have trouble controlling their emotions when watching evocative scenes, Ben Simon says. In these people, emotive regions of the brain—like the amygdala and the dorsal anterior cingulate cortex—were quick to light up, while the prefrontal cortex, which can put the brakes on runaway feelings, stayed dim. Their brains, in other words, looked like they were experiencing anxiety in overdrive.

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“When you’re dealing with something emotional, you need to recruit the prefrontal cortex to help you regulate [your reaction],” Ben Simon says. It’s the region, she explains, that’s responsible for keeping us cool and collected in times of crisis. “You fail to do that when you’re sleep-deprived,” she says.

Sleep’s restorative powers are vast, Ben Simon says, and can equip the brain to cope with adversity. So-called deep sleep, a dreamless stage characterized by the slow brain waves it produces on an electroencephalogram (EEG), seems especially important for this process, she says. The more deep sleep participants got during their night of rest, the more active their prefrontal cortices were the day after—and the better managed their emotions.

“It’s a beautiful cycle,” Ben Simon says. “Being sleep deprived takes away your emotion regulation capabilities. And then sleep, specifically deep sleep, magically brings it back online, and lets you start your day calmer.”

Pulling an all-nighter is a drastic departure from a healthy snooze schedule. But that’s not the only way to deprive yourself of sleep, says Meredith Coles, an expert in anxiety disorders at Binghamton University who wasn’t involved in the study.

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Anxiety and sleep deprivation both affect the brain's emotion processing centers, fueling a vicious cycle of stress and sleeplessness. Image Credit: amenic181, iStock

In a final experiment, Ben Simon and her team asked nearly 400 healthy people to fill out online surveys tracking their sleep quality and anxiety levels from the comfort of their own homes. Even minor disruptions to slumber, like frequent wake-ups, appeared to mess with people’s emotions: When they slept worse, they felt worse.

Historically, people have put “a lot of focus on the importance of sleep duration,” says Dana McMakin, a clinical psychologist who specializes in anxiety at Florida International University, but was not involved in the study. “But this makes it clear that sleep continuity and efficiency matter, too.”

Ben Simon hopes that sleep might someday play a role in the treatment of anxiety disorders. That has yet to be tested directly, as all the people studied in this particular paper were healthy individuals, McMakin points out. There are also probably more brain regions and pathways involved at the nexus of sleep and anxiety that have yet to be uncovered, Olatunji adds.

Still, the study hints at an exciting avenue for future research, he says, especially considering that many patients with anxiety disorders don’t respond to typical interventions.

Even for those hoping to ameliorate day-to-day stress, catching high-caliber z’s can be a powerful palliative, Coles says. After all, “there aren’t too many risks to just getting more sleep,” she says. “In my experience, the benefits to doing so...tend to come out even stronger than we predict.”

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