If you’re wondering when you’ll start to need things like more sleep and reading glasses, well, a new study is narrowing down the ages when you can expect to feel a lot older.

Decide if you want to know and then read on or don’t.

A recent study, published in Nature Aging, tracked thousands of people from age 25-75 and detected one major wave that begins around age 44, and another that starts at age 60.

The researchers believe the findings explain why certain health issues, like cardiovascular disease or musculoskeletal problems, arise at those times.

108 volunteers submitted blood and stool samples, as well as skin, oral, and nasal swabs for 7 years. They assessed RNA molecules, proteins, metabolites, microbes, and more before drawing any conclusions.

What they found was that most molecules and microbes did not shift gradually, but in clusters in people’s mid-40s and early 60s.

They adjusted for changes brought on by menopause, because they found the same alterations in men in their mid-40s, says first author Dr. Xiaotao Shen.

“This suggests that while menopause or perimenopause ay contribute to the changes observed in women in their mid-40s, there are likely other, more significant factors influencing these changes in both men and women.”

The first wave of changes are linked to cardiovascular disease and the ability to metabolize caffeine, alcohol, and lipids.

The second wave included molecules involved in immune regulation, carbohydrate metabolism, and kidney function.

Molecules related to skin and muscle aging shift at both age points.

More research is needed to account for the impact of lifestyle and behavioral factors, but this seems to indicate that there is a reason some conditions spike after a certain age instead of gradually increasing with age.

So, now you know what to look out for.

But you still can’t do anything to change it.

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