Better sleep, less fear

Rapid eye movement sleep may dampen sensitivity to fearful stimuli

October 23, 2017

Science Daily/Society for Neuroscience

Higher quality sleep patterns are associated with reduced activity in brain regions involved in fear learning, according to a study of young adults. The results suggest that baseline sleep quality may be a useful predictor of susceptibility to post-traumatic stress disorder (PTSD).

Sleep disturbances are a common feature of PTSD. While previous research has focused on understanding how single nights of sleep influence the maintenance of already-established fear memories, few studies have investigated whether an individual's regular sleeping habits prior to trauma contributes to the acquisition of these fear memories.

Itamar Lerner, Shira Lupkin and their colleagues at Rutgers University had students monitor their sleep at home for one week using unobtrusive sleep monitoring tools, including a headband that measures brain waves, a bracelet that measures arm movements, and a sleep log. The students then participated in a neuroimaging experiment during which they learned to associate a neutral image with a mild electric shock. Students who spent more time in rapid eye movement (REM) sleep -- the phase when dreaming occurs -- exhibited weaker modulation of activity in, and connectivity between, their amygdala, hippocampus and ventromedial prefrontal cortex during fear learning.

The authors replicated these results in a second study using traditional polysomnographic monitoring of sleep during the night just prior to fear learning. Taken together, the findings are consistent with the idea that REM sleep reduces levels of norepinephrine in the brain, which may dampen an individual's sensitivity to fearful stimuli. 

https://www.sciencedaily.com/releases/2017/10/171023140920.htm

Prevalence of diagnosed sleep disorders has risen among US veterans

Largest rate increases among those with post-traumatic stress disorder

July 15, 2016

Science Daily/American Academy of Sleep Medicine

A new study found a six-fold increase in the age-adjusted prevalence of any sleep disorder diagnosis over an 11-year period among US veterans. The largest increases were identified in patients with post-traumatic stress disorder (PTSD), other mental disorders, or combat experience. Results also show that the prevalence of PTSD tripled during the study period.

In a sample of more than 9.7 million U.S. veterans, the age-adjusted prevalence of sleep disorders increased from less than 1 percent in 2000 to nearly 6 percent in 2010. Sleep apnea was the most common sleep disorder diagnosis (47 percent) followed by insomnia (26 percent). Veterans with cardiovascular disease, cancer, or other chronic diseases also experienced higher rates of sleep disorder diagnoses relative to those without comorbid conditions.

Study results are published in the July issue of the journal Sleep.

"Veterans with PTSD had a very high sleep disorder prevalence of 16 percent, the highest among the various health conditions or other population characteristics that we examined," said Principal Investigator and senior author James Burch, PhD, Associate Professor in the Department of Epidemiology and Biostatistics in the Arnold School of Public Health at the University of South Carolina. "Because of the way this study was designed, this does not prove that PTSD caused the increase in sleep disorder diagnoses," noted Burch, who also is a Health Science Specialist at the WJB Dorn Department of Veterans Affairs Medical Center in Columbia, South Carolina. "However, we recently completed a follow-up study, soon to be submitted for publication, that examined this issue in detail. In that study, a pre-existing history of PTSD was associated with an increased odds of sleep disorder onset."

According to the American Academy of Sleep Medicine, sleep apnea is a sleep-related breathing disorder characterized by abnormalities of respiration during sleep. The most common form of sleep apnea is obstructive sleep apnea, which is characterized by repetitive episodes of complete or partial upper airway obstruction occurring during sleep. Insomnia involves a frequent and persistent difficulty initiating or maintaining sleep that results in general sleep dissatisfaction and daytime impairment.

The study population consisted of all U.S. veterans seeking care in the Veterans Health Administration system between FY2000 and FY2010. Of the total sample of 9,786,778 veterans, 93 percent were men, and 751,502 were diagnosed with at least one sleep disorder.

https://www.sciencedaily.com/releases/2016/07/160715112939.htm