By Michael Smith, North American Correspondent, MedPage Today
Published: June 10, 2008
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco  Earn CME/CE credit for reading medical news

BALTIMORE, June 10 — The early bird gets the A.

The benefit of being a morning person was a “full letter-grade difference,” Dr. Taylor said at SLEEP 2008, the annual meeting of the Associated Professional Sleep Societies.

The researchers enrolled 824 psychology students at the university, who completed a health survey that included questions on sleep habits and daytime functioning.

Volunteers also completed the Morningness/Eveningness Questionnaire, or MEQ, which identified their circadian rhythm type — whether a student was a morning or evening person.

Kendra Clay, an undergraduate at the university who was lead author, said the investigators ran a multiple linear regression analysis with cumulative grade-point average as the dependent variable. There were also a range of other factors — including SAT scores, academic and social ability, and MEQ results — as independent variables.

The final model included academic ability, social ability, SAT verbal scores, and MEQ score. It predicted 21% of the variability in grade-point average, Clay said. The finding was significant at P<0.001.

With other factors held constant, the model showed that for every standard deviation increase in MEQ — toward being a morning person — there was a 0.148 standard deviation increase in cumulative GPA.

Put another way, if the MEQ score was zero — indicating an extreme evening person — the GPA was just under 2.5 and it increased linearly to just under 3.5 at the other end of the 30-point scale.

The Texas study was one of several here looking at the effects of circadian rhythm and sleep disturbances on academic performance:

Fred Danner, Ph.D., of the University of Kentucky, reported that more hours of sleep per school night among 882 high school freshmen were significantly and positively associated with GPA and level of motivation, and significantly but negatively associated with clinically significant levels of emotional disturbance and ADHD. Each additional hour of sleep on school nights lowered the odds of scoring in the clinically significant range of emotional disturbance and ADHD by 25% and 34%, respectively.

James F. Pagel, M.D., of the University of Colorado, studied insomnia in 64 psychology, nursing, and medical students who were divided into two groups based on their GPA. He found that 69.7% of those with a low GPA had difficulty falling asleep, 53.1% had leg kicks or twitches at night, 65.6% reported waking at night and having trouble falling back to sleep, and 72.7% had difficulty concentrating during the day.

The findings are not unexpected, according to Gaby Badre, M.D., Ph.D., a sleep specialist at the University in Gothenberg in Sweden and the London Clinic in England.

“There is a tendency for young people to be phase-delayed,” said Dr. Badre, who was not involved in any of the studies.

And it makes sense that young people whose body clock is set later than the actual time would do worse, he said. “When the social clock is saying eight a.m., it’s still five a.m. to them,” he said.

The upside is that things improve with age: “As we grow older, the clock moves and we become larks rather than owls,” he said.

The researchers reported no outside funding. Dr. Taylor did not report any conflicts.

Primary source: Associated Professional Sleep Societies meeting
Source reference: Clay K, et al “Morningness and eveningness relationship to college GPA” APSS Meeting 2008; Abstract 728.

Additional source: Associated Professional Sleep Societies meeting
Source reference:
Danner FW, et al “Sleep habits, emotional disturbance, and ADHD in high school freshmen” APSS Meeting 2008; Abstract 321.

Additional source: Associated Professional Sleep Societies meeting
Source reference:
Kwiatkowski C, et al “Insomnia significantly affects the school performance of college students” APSS Meeting 2008; Abstract 709.