Not getting enough shuteye can amplify the brain's anticipatory reactions, upping overall anxiety levels, according to new research.
And the effect is particularly pronounced among people who are nervous to begin with.
"What this study highlights is the importance of sleep for healthy emotional functioning," said Andrea Goldstein, who did the research at the Sleep and Neuroimaging Laboratory at the University of California, Berkeley. "And people who are highly anxious may actually be more vulnerable."
In the new study, to be presented at the SLEEP 2012 conference in Boston this week, researchers used MRIs to look at the impact of sleep on anticipation.
Anticipation is a fundamental brain process that can play a major role in general anxiety as well as anxiety disorders. The latter are the most common mental illness in the United States, affecting more than 40 million adults.
"We all have anticipatory anxiety," explained Fugen Neziroglu, director of the Bio Behavioral Institute in Great Neck, N.Y., who was not involved with the new research.
"To some degree, it is positive," she continued. "Having moderate levels of anxiety about doing well is important. But it can be destructive when it begins to interfere with your life."
Previously, the impact of sleep deprivation on the brain mechanisms that control anticipatory reactivity had not been investigated. The new study revealed a "striking overlap" between the brain networks that help mediate anticipation and those affected by sleep loss.
When the anticipatory response of 18 adults was measured after they had a normal night's sleep and then again after they had stayed awake for 24 hours, researchers found sleep deprivation significantly amplified anticipatory activity in the brain -- particularly among people who were more anxious to begin with.
"What it emphasizes is that even below the level of being clinically diagnosed [with an anxiety disorder], they seem to be especially vulnerable to insufficient sleep," said Matt Walker, the lab's lead investigator. "What we're suggesting is that you can take people who aren't clinically anxious, and you can trigger these exaggerated emotional responses in the brain."
Walker acknowledged that the new study, which is small and preliminary, does not necessarily mirror real-world scenarios, given that people are seldom awake for 24 hours at a time.
However, he argued, the study still has insights to offer and begs for further investigation. People must stay up for long periods of time in many fields in which appropriate responses to anticipation and anxiety are absolutely essential.
"There are a number of professions where sleep deprivation is rife -- aviation, in the military, in the medical profession," Walker explained. "These are fields where most people wouldn't have to think long about how appropriately anticipating an event is essential. So I think the translational relevance is there."