Specifically they found that a week of a lack of sleep increased tau. One night of disrupted sleep increased amyloid beta, CBS News reported.
After adjusting for factors like age and family history of the disease, scientists found that poor sleep quality, sleepiness in the daytime and other sleep problems were linked to those spinal fluid indicators of Alzheimer's, The New York Times reported.
Scientists are not fully sure why the two are linked, but said that while examining animals, they found that the brain clears toxins while the animal sleeps.
They say it could be the same for people.
But scientists warn that not all people who have sleep problems are going to develop Alzheimer's disease, The New York Times reported.
According to the Alzheimer's Association, there are more than 5 million Americans living with the disease. It could increase as high as 16 million by 2050. It is the sixth leading cause of death in the U.S.