From business-standard.com
Scientists have found that disrupted circadian rhythms may keep the brain alert at night, preventing the mental disengagement needed to fall and stay asleep
Your body may be ready for sleep, but your mind just refuses to wind down. For millions of people living with insomnia, this phenomenon occurs every night.
According to new research, the solution to this phenomenon may lie in the body’s internal clock. In a study titled Cognitive-affective disengagement: 24h rhythm in insomniacs versus healthy good sleepers, published in the journal Sleep Medicine, scientists have found that in people suffering from chronic insomnia, the mental clock, or the day-night rhythm of mental activities, is delayed and weaker in comparison to healthy individuals. This delays the process of moving from a sharp mental state to a dull mental state, which enables the start of sleep.
According to scientists at the University of South Australia, this delayed mental clock may be the reason for the constant mental activity in people suffering from insomnia.
What did the study find about Insomnia and Circadian rhythms?
For the study, 16 older adults with sleep-maintenance insomnia and 16 healthy adults with good sleeping habits were monitored for 24 hours under a ‘constant routine’ condition, where the lights were dim, no naps were allowed, and food was controlled, among other conditions.
Every hour, the participants were asked to rate the content of their thoughts, including the tone, quality and controllability of the thoughts.
The researchers found that mental activity has a predictable daily pattern in good sleepers. Afternoon mental activity is more structured, goal-oriented and reality-based. But as night approaches, the mind gradually changes. Mental activity becomes image-based, dream-like, unstructured and unrelated to goal-oriented activity.
They found clear circadian rhythms in healthy sleepers, with peaks in mental engagement in the afternoon and troughs in the early morning.
The researchers found 24-hour rhythms in people with insomnia as well, but their rhythms were flatter and delayed.
Three major differences stood out:
- Delayed peaks: Their cognitive peaks were delayed by about 6.5 hours. In effect, their brains were still running daytime-style thinking deep into the night.
- Reduced amplitude: The difference between their daytime alertness and night-time quietening was smaller. Scientists call this reduced “circadian amplitude”.
- Persistent sequential thinking: Insomniacs showed more “sequential” thinking, thoughts that move step-by-step in a logical chain, especially at night.
In other words, their brains failed to downshift.
Is Insomnia just anxiety, or is there a brain link?
According to the study, anxiety levels were higher in insomniacs. Anxiety has been known to produce sequential thinking. However, the researchers do not consider anxiety to be the main reason for insomnia.
The study shows that it is possible that insomnia and anxiety have similar underlying causes in the brain. This is the hyperactivity of the prefrontal regions of the brain. The mind may not be willing to give up control.
What does cognitive hyperarousal mean in Insomnia?
Many people with insomnia describe a “racing mind”. Scientists refer to this as cognitive hyperarousal, a state in which the brain remains alert and engaged when it should be disengaging.
However, the hyperarousal may not just be psychological. It may be driven by a misaligned internal clock that keeps cognitive systems active too late into the night.
Sleep, as the authors note, is not merely closing your eyes; it requires the brain to disengage from goal-directed thought.
Can strengthening circadian rhythms help treat insomnia?
According to the researchers, if insomnia involves weakened or delayed circadian signals, then therapies aimed at strengthening daily rhythms could help. The researchers highlight interventions such as:
- Timed bright light exposure
- Structured daily routines
- Activity scheduling
- Mindfulness-based therapies to reduce sequential thinking
Mindfulness, in particular, may interrupt linear, chain-like thinking and encourage a more non-judgmental mental state, closer to the cognitive drift that precedes sleep.
If confirmed in larger studies, treatment could become more personalised to realign the brain clock of people suffering from insomnia.
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