Poor sleep may hamper the ability to see things in positive light, especially in people suffering from depression and anxiety, researchers including one of Indian origin have found.
Researchers from University of Illinois at Chicago (UIC) in the US, used functional MRI to measure the activity in different regions of the brain as subjects were challenged with an emotion-regulation task.
They studied about 78 patients, 18 to 65 years of age, who had been diagnosed with an anxiety disorder, a major depressive disorder, or both.
The participants were given a questionnaire to assess their sleep over the previous month.
They were shown disturbing images of violence - from war or accidents and were asked to simply look at the images and not to try to control their reaction or to "reappraise" what they saw in a more positive light.
An example of reappraisal would be to see an image of a woman with a badly bruised face and imagine her as an actress in makeup for a role, rather than as a survivor of violence, said researchers.
A motion-sensing device called an actigraph measured their awake time in bed, or "sleep efficiency," over a six-day period.
Researchers, including Anand Kumar from University of Illinois at Chicago, found that participants who reported poorer sleep on the questionnaire were seen to have less brain activity in the dorsal anterior cingulate cortex during the reappraisal (DACC) task, while those with lower sleep efficiency based on the actigraph data had higher activity in the DACC.
The questionnaire results indicated that three out of four participants met criteria for significant sleep disturbance, and the actigraph results suggested the majority had insomnia, researchers said.
"Since the questionnaire and actigraph measure different aspects of the sleep experience, it is not surprising that brain activity also differed between these measures," said Heide Klumpp, assistant professor of psychiatry at UIC.
"The questionnaire asks about sleep over the previous month and answers can be impacted by current mood," Klumpp said.
"Plus, respondents may not be able to accurately remember how they slept a month ago. The actigraph objectively measures current sleep, so the results from both measurements may not match," she said.
"Higher DACC activity in participants with lower levels of sleep efficiency could mean the DACC is working harder to carry out the demanding work of reappraisal," Klumpp said.
"Our research indicates sleep might play an important role in the ability to regulate negative emotions in people who suffer from anxiety or depression," she said.
The study was published in the journal Depression and Anxiety.