PITTSBURGH (KDKA) – Could the answer to staying slim and sharp be as simple as sleep?

Two recent studies address this.

A study from the University of Colorado had eight men and women, with an average age 22, sleep in a lab for two weeks.

They gained almost two pounds over five nights when they were limited to five hours sleep. They did eat more, but hunger hormones responded as expected and didn’t explain this.

When participants were allowed nine hours, they ate less.

“If you’re gaining weight, I would recommend a person have a sleep study performed, especially if they’ve gained more than 10 percent of their body weight,” says Dr. Andrew Perez, a sleep specialist at St. Clair Hospital. “Diagnosing someone with sleep apnea, or sleep disorder, you might be able to help them sleep better and that might help them maintain their body weight back to the ideal.”

In a different study from Washington University, 145 volunteers with normal thinking and memory, ages 45 to 75, kept sleep diaries for two weeks. Researchers had already analyzed their spinal fluid for markers of amyloid plaques in the brain, which are abnormalities associated with Alzheimer’s disease. Those with markers had poorer sleep efficiency compared to those without — that is, just as much time in bed, but less time asleep.

This leads to the question: “Is the Alzheimer’s disease impacting the sleep, or is the sleep causing the progression of Alzheimer’s?” Perez asked. “Which came first, sort of, the chicken or the egg?”

Sleep experts recommend seven to eight hours of sleep as ideal. If you’re having weight gain or thinking problems with no other explanation, a sleep study may add something to your evaluation.