Lack of sleep may increase dementia risks, study finds Published: Tags: WESTON, Fla. – A word to the weary: if you’re getting six or less hours of shut eye a night, a new study finds you could be putting your brain health at risk. “Sleep affects so many aspects of our lives, our brain function cardiovascular system and so many other things. In this recent study where they looked at about 8,000 patients and they followed them over 25 years or so what they found was patients who got less sleep, especially less than 6 hours in their 50s and 60s had a much greater risk of developing dementia almost 20%,” said Dr. Samuel Gurevich, a pulmonologist and sleep specialist with the Cleveland Clinic Weston.