Adelaide: Australian researchers have discovered evidence that insomnia may be connected to disruptions in the brain’s natural 24-hour rhythm of mental activity. This breakthrough provides insight into why some individuals find it difficult to ‘switch off’ at night.
According to Emirates News Agency, the study, published in Sleep Medicine and led by the University of South Australia (UniSA), is the first to map the fluctuations in cognitive activity throughout the day in individuals with chronic insomnia, as compared to healthy sleepers. Insomnia impacts approximately 10 percent of the population and up to 33 percent of older adults, with many experiencing an overactive or racing mind during the night. While cognitive hyperarousal has long been linked to insomnia, the underlying causes have remained unclear.
The study investigated whether the inability to reduce mental activity at night, a core feature of insomnia, is a reflection of circadian rhythm abnormalities. In a controlled laboratory setting, 32 older adults (16 with insomnia and 16 healthy sleepers) were monitored over 24 hours of wakeful bedrest. This environment eliminated external cues, allowing scientists to focus on the brain’s internal rhythms. Participants remained in a dimly-lit room, in bed, with food and activity carefully managed. They completed hourly checklists to assess the tone, quality, and controllability of their thoughts.
Both groups showed clear circadian patterns in mental activity, peaking in the afternoon and dipping in the early morning. However, there were significant differences in the insomnia group. Lead researcher, UniSA Professor Kurt Lushington, noted that unlike healthy sleepers, those with insomnia did not experience a strong transition from daytime problem-solving to nighttime disengagement. Instead, their cognitive activity remained more daytime-like during the night when the brain should be winding down.
Their cognitive peaks were delayed by about six and a half hours, suggesting that their internal clocks may promote alert thinking into the night. Professor Lushington explained that sleep involves more than closing one’s eyes; it requires the brain to disengage from goal-directed thoughts and emotional involvement. In cases of insomnia, this disengagement is blunted and delayed, likely due to circadian rhythm abnormalities, meaning the brain doesn’t receive the necessary signals to ‘power down’ at night.
Co-author, UniSA Professor Jill Dorrian, emphasized that the findings suggest new treatment opportunities for insomniacs, such as interventions that strengthen circadian rhythms. This could include timed light exposure and structured daily routines to restore the natural day-night variation in thought patterns. Practicing mindfulness may also assist in quieting the mind at night.
The researchers suggest that current treatments often focus on behavioral strategies, but these findings indicate that tailored approaches addressing circadian and cognitive factors could offer a solution.
