Short sleep duration is common among redeployed soldiers – particularly those who experience combat – and is associated with numerous impairments, including posttraumatic stress disorder, according to findings from a cross-sectional study of more than 2,700 members of a brigade combat team.
Mean sleep duration was 5.8 hours among the soldiers, who were surveyed 90-180 days after completion of a 6-15 month deployment to Iraq as part of Operation Iraqi Freedom. The majority (72%) of the 2,738 subjects reported short sleep duration – with 43% reporting less than 7 hours nightly (short sleep duration), and 29% reporting less than 6 hours nightly (very short sleep duration), David D. Luxton, Ph.D., and his colleagues reported.
Symptoms of insufficient sleep were reported by 16% of the subjects, and were much more common among those with short sleep duration (odds ratio, 2.9) and those with very short sleep duration (OR, 9.8), compared with those with normal sleep duration, said Dr. Luxton, of the National Center for Telehealth & Technology, Defense Centers of Excellence for Psychological Health and Traumatic Brain Injury in Tacoma, Wash.
Short sleep duration was significantly more common among the 77% of subjects who reported experiencing combat (OR, 0.44), particularly among those who were wounded or injured during combat operations (Sleep 2011;34:1189-95).
The prevalence of medical comorbidities and high-risk behaviors varied based on sleep duration; those with very short sleep duration were at greater risk for all conditions, compared with those with either short or normal sleep duration, the investigators noted.
Furthermore, symptoms of insufficient sleep independently predicted PTSD, depression, mild traumatic brain injury, panic syndrome, and suicide risk, they said.
Among those who met screening criteria for PTSD, 37% reported symptoms of insufficient sleep, and in fact, the strongest predictor of PTSD was sleep duration of less than 6 hours nightly (adjusted OR, 4.7).
Depression also was strongly associated with sleep duration and symptoms of insufficient sleep (adjusted OR, 7.9 and 2.5, respectively), and while mild traumatic brain injury was most strongly associated with combat exposures (adjusted OR, 16.7), it was also associated with very short sleep duration (adjusted OR, 1.8) and symptoms of insufficient sleep (adjusted OR, 1.8 and 2.0, respectively).
Panic syndrome was associated with very short sleep duration and symptoms of insufficient sleep (adjusted OR, 3.9 and 3.0, respectively). Also, very short sleep duration – but not short sleep duration, predicted obesity, and tobacco and alcohol abuse (adjusted OR, 3.3), and both very short sleep duration and symptoms of insufficient sleep predicted suicidal ideation or having attempted suicide (adjusted OR, 3.8 and 2.4, respectively).
Short sleep duration also has been shown in prior studies to be linked with many deleterious outcomes. Few studies, however, have detailed sleep disturbances associated with war or traumatic events or among deployed soldiers, and none have assessed postdeployment sleep duration and comorbid illnesses in a redeployed combat arms unit such as this one, the investigators noted.
Data for the study were collected in 2007 as part of the Health Risk Assessment II project initiated by the Department of Defense, which incorporated many previously validated mental health screening instruments. Subjects were a mean age of 25.5 years, 55% had completed a second, third, or fourth deployment in support of the global war on terror when they were enrolled in the study, and the mean length of their most recent deployment was 398 days.
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