A preliminary study published in Neurology, has found that when young, healthy men were deprived of just 1 night of sleep, they had higher levels of tau in their blood than when they had a full, uninterrupted night of rest.
In the study, participants had an average 17% increase in serum tau levels after a night of sleep deprivation compared to an average 2% increase after a good night of sleep. Levels of 4 other biomarkers associated with Alzheimer disease (AD) did not differ between a good night of sleep and 1 night of no sleep.
“Many of us experience sleep deprivation at some point in our lives due to jet lag, pulling an all-nighter to complete a project, or even doing shift work, working overnights or inconsistent hours,” said study author Jonathan Cedernaes, MD, PhD, from Uppsala University in Sweden. “Our exploratory study shows that even in young, healthy individuals, missing 1 night of sleep increases the level of tau in blood suggesting that over time, such sleep deprivation could possibly have detrimental effects.”
The study involved 15 healthy, normal-weight men with an average age of 22. They all reported regularly getting 7 to 9 hours of quality sleep per night. The main limitation of the study was its small size. In addition, it looked only at healthy young men, so the results may not be the same for women or older people.
For each of the 2 phases, the men were observed under a strict meal and activity schedule in a sleep clinic for 2 days and nights. Blood samples were taken in the evening and again in the morning. For 1 phase, participants were allowed to get a good night of sleep both nights. For the other phase, participants were allowed to get a good night of sleep the 1st night followed by the 2nd night of sleep deprivation. During sleep deprivation, lights were kept on as participants sat up in bed playing games, watching movies, or talking.
“It’s important to note that while higher levels of tau in the brain are not good, in the context of sleep loss we do not know what higher levels of tau in blood represent,” said Cedernaes. “When neurons are active, production of tau in the brain is increased. Higher levels in the blood may reflect that these tau proteins are being cleared from the brain or they may reflect elevated tau levels in the brain. Future studies are needed to investigate this further, as well as to determine how long these changes in tau last, and to determine whether changes in tau in blood reflects a mechanism by which recurrent exposure to restricted, disrupted or irregular sleep may increase the risk of dementia. Such studies could provide key insight into whether interventions targeting sleep should begin at an early age to reduce a person’s risk of developing dementia or AD.”
Michelle L. Dougherty, MD, FAES, FAAN
Jill M. Giordano Farmer, DO
Fabio Fieni Toso, MD; Rene de Araújo Gleizer, MD; and Lívia Almeida Dutra, MD, PhD