Here’s Why Some Insomniacs Can’t Sleep

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WWe’ve all been there. Lying awake in our beds, unable to shake off the worries and stress of the coming day(s) when we should drift peacefully into dreamland. For some of us, it’s an unfortunate nightly ritual.

New research shows that people with chronic difficulty falling asleep may suffer from a disruption in the brain’s ability to switch from awake problem solving during the day to necessary nighttime downtime, a 24-hour cycle. In short, insomniacs’ brains fail to disengage at the appropriate time, continuing to process the concerns of the day well past bedtime.

A team of sleep scientists from universities in Australia and the United States published their results in Sleep medicine.

Researchers followed 32 elderly people – 16 healthy sleepers and 16 insomniacs – for 24 hours. During this period, participants were isolated in beds without environmental or behavioral cues to alert them of the time of day. This dimly lit setup effectively meant that the volunteers’ brain activity – which the scientists assessed hourly using checklists capturing data on the quality and controllability of their thoughts – was influenced exclusively by the internal circadian rhythms that flow through us all.

Read more: »How your body knows what time it is»

By observing these different sleepers, the scientists discovered that they all had natural peaks in brain activity in the afternoon and troughs in the early morning. But people who had trouble falling asleep failed to transition between these two states effectively. “Unlike good sleepers, whose cognitive state shifted predictably from daytime problem-solving to nighttime disengagement, those with insomnia failed to downgrade as sharply,” University of South Australia clinical psychologist and co-author Kurt Lushington said in a statement. “Their thought patterns remained more daytime-like during the night, when the brain should be calming down.”

The problem, Lushington and colleagues suggest, might be that the insomniacs’ circadian rhythms were off from hour to hour. “Our study shows that in insomnia, this disengagement is attenuated and delayed, likely due to circadian rhythm abnormalities,” Lushington added. “This means the brain doesn’t get strong signals to turn off at night.”

Some of the few insomniacs in the study showed distinct differences in thought structure, with high levels of sequential thinking — which typically indicates step-wise problem solving and activates the brain’s language and decision-making centers, but can be indicative of depression and anxiety — extending into sleeping hours. But the abnormalities in circadian rhythms suggested by the findings open the door to more tailored interventions for people whose minds keep racing once their head hits the pillow. “These include scheduled light exposure and structured daily routines that can restore the natural day-night variation in thought patterns,” said Jill Dorrian, a sleep psychologist and co-author from the University of South Australia.

What keeps any of us from entering the restorative realm of sleep at night, it’s good to know that there are scientists probing the rhythm of our thoughts for clues that will help us get some sleep.

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Main image: Blueastro / Shutterstock

• Bob Grant

  Published on December 3, 2025

  Bob Grant is the associate editor of Nautilus.