Sleep Phase Can Reduce Anxiety in PTSD Patients

A recent study suggests that sleep spindles, which are small bursts of brain activity detected by EEG during one period of sleep, may regulate anxiety in persons suffering from post-traumatic stress disorder (PTSD). The work sheds light on the role of spindles in PTSD anxiety relief and verifies their previously documented role in the transfer of new information to long-term memory storage. The findings contradict previous studies that found spindles may increase obsessive and aggressive thoughts in patients suffering from PTSD.

On May 3, 2023, the final draft of the preprint will be published in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.

“These findings may be meaningful not only for people with PTSD, but possibly for those with anxiety disorders,” said senior author Anne Richards, MD, MPH, of the UCSF Department of Psychiatry and Behavioral Sciences, the Weill Institute for Neurosciences and the San Francisco VA Medical Center.

“There are non-invasive ways that might harness the benefits of this sleep stage to provide relief from symptoms,” she said.

The researchers included 45 people who had all undergone war or noncombat trauma; roughly half of them had moderate PTSD symptoms, while the other half had milder symptoms or were asymptomatic. The spindles were observed while sleeping during non-rapid eye movement 2 (NREM2) sleep, which accounts for approximately 50% of total sleep.

Participants in the study were subjected to a “stress visit” in which they were shown photos of violent scenes such as accidents, war brutality, and human and animal damage or mutilation, followed by a two-hour lab-monitored snooze.

Anxiety surveys were administered both immediately following exposure to the images and after the nap, when the recollection of the images was examined. The anxiety levels in the stress visit were also compared to those in a control visit that did not include exposure to these images.

The spindle rate frequency was higher during the stress visit than during the control visit, according to the researchers. “This provides compelling evidence that stress was a contributing factor in spindle-specific sleep rhythm changes,” stated first author Nikhilesh Natraj, Ph.D., of UCSF’s Department of Neurology, Weill Institute for Neurosciences, and San Francisco VA Medical Center. Notably, increased spindle frequency after stress exposure reduced anxiety post-nap in participants with more severe PTSD symptoms.

The study’s naps occurred immediately after being exposed to violent images, raising the question of whether sleep happening days or weeks following trauma will have the same therapeutic impact. The researchers believe this is possible and suggest therapies that may activate the spindles associated with NREM2 sleep and aid patients suffering from stress and anxiety problems.

Prescription drugs, like Ambien, are one option that should be studied further, “but a big question is whether the spindles induced by medications can also bring about the full set of brain processes associated with naturally occurring spindles,” said Richards.

Electrical brain stimulation is another area for more study, researchers said. “Transcranial electrical stimulation in which small currents are passed through the scalp to boost spindle rhythms or so-called targeted memory reactivation, which involves a cue, like an odor or sound used during an experimental session and replayed during sleep may also induce spindles,” said Natraj.

“In lieu of such inventions, sleep hygiene is definitely a zero-cost and easy way to ensure we are entering sleep phases in an appropriate fashion, thereby maximizing the benefit of spindles in the immediate aftermath of a stressful episode,” he said.

The next endeavor for the researchers will be to investigate the role of spindles in the consolidation and replay of intrusive and violent memories many weeks after trauma exposure.

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