This study, led by the University of South Australia (UniSA), is the first of its kind to map fluctuations in cognitive activity throughout the day in individuals with chronic insomnia, compared to healthy individuals.
The inability to regulate mental activity at night—a hallmark of insomnia—was a central focus of this study. Under strictly controlled laboratory conditions, 32 elderly individuals (16 with insomnia and 16 healthy) were monitored for 24 hours of bed rest while remaining awake. This approach allowed the scientists to isolate the brain's internal rhythms.
Both healthy individuals and those with insomnia showed clear rhythmic patterns of mental activity, peaking in the afternoon and reaching their lowest point in the early morning. However, several key differences emerged within the insomnia group.
Professor Kurt Lushington, the lead researcher on the study, explains: “Unlike people who get a good night’s sleep, whose cognitive state predictably shifted from problem-solving during the day to detachment from thinking at night, those with insomnia failed to make this shift with the same force. Their thinking patterns remained more like those of the day during the night hours when the brain should be resting.”
Their peak cognitive activity was also delayed by about six and a half hours, suggesting that their internal clocks may encourage vigilant thinking until late at night.
Professor Lushington adds: "Sleep is not just about closing your eyes, it's about the brain disconnecting from goal-oriented thinking and emotional engagement. Our study shows that this disconnection is dim and delayed in cases of insomnia, most likely due to disruptions in the circadian rhythm. This means the brain does not receive strong signals to switch off at night."
Professor Jill Dorrian, co-author of the study, points out that these findings highlight new therapeutic possibilities for insomnia patients, such as interventions that promote circadian rhythms. She adds, "These treatments include exposure to light at specific times and structured daily routines that may restore the natural night-day cycle of thought patterns. Mindfulness practices may also help calm the mind at night."
The researchers emphasize that current treatments often focus on behavioral strategies, but these results suggest that customized approaches that address circadian and cognitive factors could offer an effective solution.
