Investigators at Harvard-affiliated Brigham and Women's Hospital found that those who get five or less hours of sleep per night are twice as likely to develop dementia than those who slept seven to eight hours per night. Even more, they discovered a link between sleep disturbance and sleep deficiency with overall risk of death.
They found a variety of sleep related factors influenced chances of developing dementia. For example, routinely taking 30 minutes or longer to fall asleep was associated with a 45 percent greater risk for incident dementia, while "routinely experiencing a difficulty in maintaining alertness, routinely napping, reporting poor sleep quality, and sleeping five or fewer hours per night was also associated with increased risk of death." Just a thought.