Public Release: 

Amino acid identified associated with poor performance under sleep restriction

Findings advance ability to predict an individual's performance under 5 consecutive nights of 4 hours in bed

University of Pennsylvania School of Medicine

DENVER - The amino acid acetylcarnitine may help predict an individual's neurobehavioral performance during chronic sleep restriction, according to results of a new study (abstract 0251) from researchers at the Perelman School of Medicine at the University of Pennsylvania that will be presented at SLEEP 2016, the 30th annual meeting of the Associated Professional Sleep Societies LLC.

Previous studies have shown that sleep loss degrades behavioral attention, cognitive processing and memory, but this study offers the first experimental evidence that acetylcarnitine -- which transports fatty acids into the mitochondria where they are broken down and oxidized and formed into energy -- may predict neurobehavioral vulnerability to sleep loss in healthy adults.

In the study at the sleep lab at the Hospital of the University of Pennsylvania, participants' blood samples were taken after 10-12 hours of fasting following one night of baseline sleep (10 hours time in bed), chronic sleep restriction (5 consecutive nights of 4 hours time in bed), and one night of recovery sleep (12 hours time in bed).

The Psychomotor Vigilance Test (PVT), the Digit Symbol Substitution Task (DSST), the Digit Span Task (DS), the Karolinska Sleepiness Scale (KSS) and the Profile of Mood States (POMS) tests were administered every two hours while participants were awake.

The preliminary data associated acetylcarnitine with six neurobehavioral variables during sleep loss, including PVT lapses (longer than 500 millisecond responses) and errors, PVT response speed, DSST total correct, DS total correct, KSS scores, and POMS vigor scores -- but not at baseline or recovery. Higher levels of this molecule predicted poorer behavioral attention, slower ability to process information, and poorer memory and increased sleepiness.

"We know that there are robust differences in how individuals respond to sleep loss," said Namni Goel, PhD, a research associate professor of psychology in Psychiatry in the division of Sleep and Chronobiology, and lead author on the study. "Some people are very vulnerable, while others are more resistant to these effects. Identifying this marker is an important step in identifying measures to mitigate the disruptive effects of sleep loss in those who are more affected."

The findings have implications for government agencies and other institutions interested in predicting who may be vulnerable to sleep loss and finding ways to offset the negative effects of sleep loss when they occur.

These data build on earlier work by members of the Penn team, who previously found two markers of sleep debt that reliably track when a person is sleep deprived (Weljie et al 2015, PNAS 112(8):2569-74).

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Co-authors on the study include Arjun Sengupta, Ted Abel, Amita Sehgal, Aalim M. Weljie, and senior author David F. Dinges, all from Penn, as well as Peter Meerlo from the University of Groningen in The Netherlands.

This work was supported by the Department of the Navy, Office of Naval Research Award No. N00014-11-1-0361 (NG); NASA NNX14AN49G (NG); NIH grant R01 NR004281 (DFD); the National Space Biomedical Research Institute (NSBRI) through NASA NCC 9-58 (DFD); Clinical and Translational Research Center (CTRC) grant UL1TR000003; Defense Advanced Research Projects Agency (DARPA) and the U.S. Army Research Office (TA, W911NF1010093).

Penn Medicine is one of the world's leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania(founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System, which together form a $5.3 billion enterprise.

The Perelman School of Medicine has been ranked among the top five medical schools in the United States for the past 18 years, according to U.S. News & World Report's survey of research-oriented medical schools. The School is consistently among the nation's top recipients of funding from the National Institutes of Health, with $373 million awarded in the 2015 fiscal year.

The University of Pennsylvania Health System's patient care facilities include: The Hospital of the University of Pennsylvania and Penn Presbyterian Medical Center -- which are recognized as one of the nation's top "Honor Roll" hospitals by U.S. News & World Report -- Chester County Hospital; Lancaster General Health; Penn Wissahickon Hospice; and Pennsylvania Hospital -- the nation's first hospital, founded in 1751. Additional affiliated inpatient care facilities and services throughout the Philadelphia region include Chestnut Hill Hospital and Good Shepherd Penn Partners, a partnership between Good Shepherd Rehabilitation Network and Penn Medicine.

Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2015, Penn Medicine provided $253.3 million to benefit our community.

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