MINNEAPOLIS - As the dark clouds cast shadows and the days become shorter, you might find yourself feeling a little sleepy. Before you know it, you'll wake to darkness and go home to darkness. But if you don't catch the needed zzz's, your health might suffer.

Dr. Michael Howell of Fairview Sleep Center in Edina says sleep is just as important for our health as diet and an active lifestyle with exercise.

“Health is a three-legged stool. If you are missing sleep, which is a third of our lives normally -- your body is not rejuvenating itself,” he said.

Howell says when we sleep, our brain cleans itself.

“Sleep is critically important in flushing out toxins,” Howell said. “If you aren't sleeping well you get a buildup of toxins and they can lead to Alzheimer’s disease and Parkinson's disease. The (protein) builds up normally throughout the day. If you are sleeping well it gets flushed out. If you are not sleeping well it builds up and you can get Alzheimer's disease and other related conditions.”

Nearly two-thirds of Americans do not get a full eight hours of sleep per night. But before lack of sleep leads to problems with your health, Howell says you can improve your habits.

Example, he recommends going to and waking up at the same time every day. He also says a cooler room help.

“We tend to sleep better if the temperature is between 61 and 68 degrees,” he said. “Sleep is critically important for brain health. We learn things and we remember things better, our mood is better and we are less anxious.”