Sleep spindles, which are brief bursts of brain activity occurring during a phase of sleep, may regulate anxiety in people with post-traumatic stress disorder (PTSD), according to a new research.
Challenging the findings of a recent work by other researchers, which indicated that spindles may heighten intrusive and violent thoughts in people with PTSD, this study from University of California – San Francisco (UCSF), US, throws light on their role in alleviating anxiety in PTSD as well as in the transfer of new information to longer-term memory storage.
”These findings may be meaningful not only for people with PTSD, but possibly for those with anxiety disorders,” said senior author Anne Richards, of the UCSF Department of Psychiatry and Behavioral Sciences.
She said that there were non-invasive ways to harness the benefits of this sleep stage to provide relief from symptoms.
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The findings are published in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.
The researchers studied the spindles during non-rapid eye movement 2 (NREM2) sleep, the phase of sleep when they mainly occur, which comprises about 50 per cent of total sleep, in 45 participants who had all experienced combat or noncombat trauma.
Approximately half had moderate symptoms of PTSD and the other half had milder symptoms or were asymptomatic. They were made to attend a ”stress visit” in which they were shown images of violent scenes, such as accidents, war violence, and human and animal injury or mutilation, prior to a lab-monitored nap that took place about two hours later.
Anxiety surveys were conducted immediately after exposure to the images as well as after the nap when recall of the images was tested. The researchers also compared anxiety levels in the stress visit to those in a control visit without exposure to these images.
The researchers found that spindle rate frequency was higher during the stress visit than during the control visit, thus, providing compelling evidence of stress contributing to spindle-specific sleep rhythm changes, according to Nikhilesh Natraj of the UCSF Department of Neurology.
Notably, in participants with greater PTSD symptoms, the increased spindle frequency after stress exposure reduced anxiety post-nap.
The naps in the study took place shortly after exposure to violent images – raising a question about whether sleep occurring days or weeks after trauma will have the same therapeutic effect.
The researchers think this is likely and point to interventions such as prescription drugs like Ambien and electrical brain stimulation that could trigger the spindles associated with NREM2 sleep and benefit patients with stress and anxiety disorders.