A new study suggests that a lack of deep sleep may be a key factor behind rising anxiety levels, particularly in older adults.
Researchers at the University of California, Berkeley studied 61 adults over age 65 who reported varying levels of anxiety. The participants spent a night in a sleep lab, where their brain activity was monitored with polysomnography. This test tracks brain waves, with a focus on slow-wave activity, which is the hallmark of deep, non-REM sleep.
Before and after sleeping, the participants completed questionnaires to measure their anxiety. The next morning, researchers used MRI scans to examine changes in brain regions that control emotional regulation, such as parts of the limbic system. A smaller group of participants was followed for about four years to see if the link between sleep and anxiety held over time.
The results showed a clear pattern. Older adults who had stronger slow-wave sleep reported lower anxiety levels. Those whose deep sleep was more disrupted were more likely to feel anxious the next day.
Brain scans provided an additional clue. Age-related shrinkage in emotion-processing areas, including the amygdala, insula, and cingulate cortex, was linked to less slow-wave sleep. This suggests that structural changes in the brain can weaken its ability to produce restorative deep sleep. However, even among individuals with some brain atrophy, those who maintained stronger slow-wave sleep showed better emotional stability.
The researchers concluded that impaired deep sleep essentially explained the connection between brain changes and next-day anxiety.
Deep sleep helps the brain regulate emotions. During slow-wave sleep, the nervous system shifts into a “rest-and-recover” state. Stress hormones decrease, heart rate variability improves, and the brain recalibrates circuits involved in emotional control. This stage also strengthens communication between the prefrontal cortex, the brain’s rational control center, and the limbic system, which processes fear and stress.
When deep sleep declines, the emotional regulation system becomes less stable. This can lead to heightened reactivity, more persistent worry, and a greater tendency toward anxiety.
While sleep naturally changes with age, research suggests that slow-wave sleep can be supported through daily habits. Consistent sleep timing, regular exercise, morning sunlight exposure, limiting alcohol in the evening, and keeping the bedroom cool and dark may all help preserve deeper sleep.
The study indicates that each night of restorative sleep gives the brain a chance to recalibrate stress and anxiety. When deep sleep fades, emotional resilience may fade with it. The findings suggest that habits supporting deeper sleep are small levers that can shape how people feel the next day.
