If this is your bedtime, you may have saved yourself from Alzheimer’s

Good news, night owls. According to a new set of research, disturbed or inconsistent sleep patterns do not raise one’s risk of developing Alzheimer’s. 

Alzheimer’s is about as nasty a disease as they come. The most common form of dementia, Alzheimer’s usually appears in older adults and is characterized by a decline in thinking abilities, memory loss, personality/behavior changes (depression, delusions, mood swings), and an overall inability to function independently. While there’s no shortage of life-threatening diseases and ailments, Alzheimer’s is a uniquely cruel condition in the sense that it can rob a person of their very identity.

Alzheimer’s is caused by the degeneration and death of brain cells, and sleep is the mind’s time to rest, regenerate, and strengthen memories. With this in mind, it makes a certain degree of sense that life-long sleep patterns may influence a person’s risk of developing Alzheimer’s decades down the line.

So, a new study just published by the American Academy of Neurology set out to examine the relationship between sleep patterns and Alzheimer’s risk. Additionally, since depression is a common symptom of Alzheimer’s, researchers were also interested to see if depressive episodes earlier in life are associated with a greater risk of developing Alzheimer’s later on.

“We know that people with Alzheimer’s disease often report depression and various sleep problems, like insomnia,” says study author Abbas Dehghan, Ph.D., of Imperial College London, in a release. “We wanted to find out if there are causal relationships between different sleep patterns and depression and Alzheimer’s.”

To that end, the study’s authors analyzed an enormous dataset collected from earlier genetic studies. In all, that data included 21,982 Alzheimer’s patients who were directly compared to 41,944 adults without Alzheimer’s. Also, 9,240 people with major depressive disorder were compared to 9,519 other adults with no signs of depression. Finally, another 446,118 people’s sleep habits were included as well.

Prior studies that had already diagnosed Alzheimer’s via either autopsy or clinical examination were used to calculate Alzheimer’s risk this time around. Then, a complex process known as Mendelian randomization was used to identify any cause and effect relationships at play between depression, sleep patterns, and Alzheimer’s risk.

All in all, this process yielded no results indicating that interrupted sleep habits can directly cause Alzheimer’s. The same was found in reference to depression; dealing with major depressive disorder earlier in life doesn’t appear to cause an increase in Alzheimer’s risk later on.

However, the study did come to a few other, somewhat surprising findings. In a bit of cautionary news for the early birds among us, researchers note that those who are at a two times greater genetic risk of developing Alzheimer’s appear to be slightly more likely (1%) to be “morning people,” sleep fewer hours in general, and are slightly less likely (1%) to suffer from insomnia throughout adolescence/adulthood. 

It’s important to clarify here, though, that the study’s authors say these conclusions in particular only indicate a small possible link between the genetic risk of Alzheimer’s and sleep patterns. Thus, they do not suggest a cause and effect relationship.

Still, the findings regarding insomnia and genetic Alzheimer’s risk are especially fascinating. Many Alzheimer’s patients struggle with falling asleep. Yet, these findings suggest that genetically predisposed individuals are somewhat less likely to experience insomnia throughout adolescence and adulthood. 

It’s apparent that more research is necessary to fully understand the complex relationships at play here, and the study’s authors suggest future studies include a more diverse population sample (this study included mostly people of European descent). 

That being said, the main findings of this research are clear. A varied sleep schedule doesn’t appear to raise one’s risk of developing Alzheimer’s, nor does a clinical depression diagnosis earlier in life.

The full study can be found here, published in Neurology.