We've all had those nights where we just can't get to sleep, and aren't able to concentrate the next day.

Dr. Charles Samuels, the Medical Director of Calgary's Centre for Sleep and Human Performance, says the fact is - sleep is connected to changes in cognitive function.

Researchers in Boston have found that a pattern of too little sleep can keep the brain from clearing protiens that are linked to Dementia, but so can a pattern of too much sleep.