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Evening-Type Military Veterans Report Worse Lifetime Posttraumatic Stress Symptoms and Greater Brainstem Activity across Wakefulness and REM Sleep
Hasler BP, Insana SP, James JA, Germain A

Individual preferences in sleep-wake timing, or morningness-eveningness, colloquially referred to as being an ?early bird? or a ?night owl,? can be associated with mental and physical health outcomes.  Various studies have linked eveningness with affective and behavioral dysregulation, including depression and sleep disturbances.  Because post-traumatic stress often includes affective disturbances, insomnia, and nightmares, Dr. Brant Hasler and his colleagues at the University of Pittsburgh investigated the relationship between eveningness and post-traumatic symptoms for military veterans exposed to combat. 

Dr. Hasler and colleagues analyzed data from a University of Pittsburgh research study (Principal Investigator: Anne Germain, PhD) of 36 combat-exposed military veterans exhibiting symptoms across the spectrum of post-traumatic stress symptoms.  The study utilized [18F]-fluoro-2-deoxy-d-glucose positron emission tomography to measure neural activity during wake periods as well as during rapid eye movement sleep.  The investigators assessed sleep via sleep diaries and polysomnography, and they assessed morningness-eveningness via self-report. The results of this project point to an association between eveningness and increased post-traumatic stress disorder symptoms throughout the lifetime, more disturbed sleep, and an increase in the frequency and intensity of nightmares.  Furthermore, eveningness was also associated with greater neural activity in posterior cingulate and brainstem regions associated with arousal and rapid eye movement sleep generation, potentially explaining the clinical symptoms.

This is the first study to report that eveningness is associated with lifetime post-traumatic stress symptoms, sleep, and brain activity among combat-exposed military veterans. These associations may provide insight into the hyperarousal symptoms characteristic of post-traumatic stress disorder. Further investigation of the role of morningness-eveningness in PTSD, including whether it might be a novel target of sleep-based treatment, would be well justified. 

Contributors:  
Brant P. Hasler, PhD; Salvatore P. Insana, PhD; Anne Germain, PhD (Department of Psychiatry, University of Pittsburgh)Jeffrey A. James, BS (Department of Radiology, University of Pittsburgh)

The results of this investigation were published in Biological Psychology.  Click here for a link to the abstract.