Brain scans reveal how poor sleep fuels negative emotions in alcohol addiction

A recent study published in the journal Drug and Alcohol Dependence suggests that poor sleep in people with alcohol use disorder is closely linked to heightened negative emotions and specific changes in brain activity. The findings indicate that treating sleep problems might be a practical way to help improve mood and emotional regulation for those recovering from alcohol addiction.

Addiction is often viewed as a three-stage cycle consisting of binge drinking, experiencing negative emotions during withdrawal, and a preoccupation or craving for the substance. Previous research indicates that sleep issues can alter mood and reward processing in the general population.

“Sleep problems in alcohol use disorder are extremely common. Prior work has found relationships between sleep disturbance and deficits in processes related to reward, negative emotional processing, and executive function, that are impacted in addictive disorders like alcohol use disorder,” said study author Erica Grodin, an adjunct assistant professor at UCLA and member of the UCLA Addictions Lab.

“However, these relationships had not been previously systematically examined in people with alcohol use disorder and the underlying neurobiology responsible for these processes had yet to be explored. Therefore, our study set to examine the relationship between sleep disturbance and alcohol-related reward processing, negative emotional processing, and executive function in people with an alcohol use disorder, and what the underlying neurobiology was.”

The researchers conducted two separate, independent studies. In the first study, the researchers recruited 115 adults who met the clinical criteria for alcohol use disorder. The participants completed a widely used questionnaire called the Pittsburgh Sleep Quality Index, which evaluates sleep habits over the past month. Based on their scores, 42 participants were classified as good sleepers, while 73 were classified as poor sleepers.

The scientists then asked the participants to complete a series of surveys designed to measure three specific addiction categories. These categories included craving and motivation, negative emotionality, and executive function. Executive function refers to the mental skills needed to control impulses, focus attention, and make deliberate decisions.

During their analysis, the scientists made sure to account for other factors that might influence the results. They controlled for variables like age, biological sex, race, and the severity of the participants’ alcohol use. This helped ensure that any differences in negative emotions were actually related to sleep, rather than how much the participants drank or their demographic background.

A subset of 52 participants from the first study also underwent functional magnetic resonance imaging. This is a type of brain scan that measures blood flow to see which areas of the brain are active in real time. While inside the scanner, participants looked at pictures of alcoholic beverages, like beer or wine, and non-alcoholic beverages, like water or coffee, to test their craving responses.

They were also shown a mix of neutral images, like everyday objects, and negative images, like car crashes or mutilated faces. Following each block of images, the participants used a button box to rate their current level of stress or their craving for alcohol. This allowed the researchers to see how their brains processed both rewarding and stressful situations.

The researchers found that poor sleepers experienced significantly more negative emotions, such as stress, anxiety, and depression, compared to good sleepers. Poor sleep did not appear to affect the participants’ levels of alcohol craving or their executive function skills. This suggests that sleep problems are specifically tied to the emotional distress aspect of addiction, rather than the impulsive or craving aspects.

The brain scans provided evidence that supported these psychological survey results. When viewing negative images, the poor sleepers showed much higher activity in the medial prefrontal cortex and the posterior cingulate cortex compared to the good sleepers. These specific brain regions belong to a network in the brain that is highly active when people ruminate.

Rumination involves repetitively thinking about negative feelings or dwelling on personal problems. The brain scan results indicate that people with alcohol use disorder who also struggle with sleep might be biologically wired to over-engage in negative thinking when faced with stressful stimuli. No differences were found between the groups when they looked at the alcohol-related images.

The scientists then conducted a second, independent study to verify their initial findings using a different measure of sleep. This second group included 102 different adults with alcohol use disorder. The researchers used the Insomnia Severity Index, a survey that evaluates the severity of insomnia symptoms, such as difficulty falling asleep or staying asleep, over the past two weeks.

Based on their responses, 47 people had no insomnia, 38 had sub-clinical or mild insomnia, and 17 had clinical insomnia. Just like in the first study, the researchers found that worse sleep was directly linked to higher levels of negative emotions. Participants with clinical and mild insomnia reported significantly more negative emotionality than those without sleep problems.

The researchers ensured these results were as accurate as possible by controlling for the number of alcohol use disorder symptoms each person had. Even when accounting for how severe their addiction was, the individuals with insomnia symptoms still showed a heightened negative emotional profile. Once again, sleep problems did not predict changes in the participants’ cravings or motivation to drink.

Finding the exact same pattern in a completely separate group of people provides strong evidence that the connection between sleep and negative emotions is a consistent feature of alcohol use disorder. It shows that the relationship holds up even when using different questionnaires.

“Our main finding was that negative emotional processing was uniquely impacted by sleep disturbance in people with an alcohol use disorder,” Grodin told PsyPost. “This means that people with an alcohol use disorder and problems sleeping have a harder time processing and responding to negative emotions than people with an alcohol use disorder who don’t have problems with sleep. We also found that regions of the brain involved in rumination and thinking about oneself were over-involved in negative emotional processing in people who have an alcohol use disorder and sleep problems. Overall, this suggests that sleep disturbance may be a promising treatment target to improve processing of negative emotions, a common trigger for drinking, in this group of people.”

While these findings provide new insights, the researchers noted a few limitations to their work. The research was observational and looked at data from a single point in time. This means the scientists cannot definitively say whether poor sleep causes negative emotions, or if experiencing negative emotions leads to poor sleep. The relationship between sleep, mood, and alcohol use is likely a complex two-way street.

Additionally, the participants in both studies were not formally diagnosed with a sleep disorder by a medical professional. Instead, they self-reported their sleep habits using standardized surveys. The researchers suggest that future studies should include individuals with medically confirmed sleep disorders to see if the brain patterns remain the same. Eventually, the scientists hope to test whether targeted treatments for sleep can actively reduce negative emotions in people recovering from alcohol addiction.

The study, “Sleep disturbance is associated with greater subjective and neural negative emotionality in people with alcohol use disorder,” was authored by Erica N. Grodin, Dylan E. Kirsch, Wave Ananda Baskerville, and Lara A. Ray.