Why Midlife Can Feel Like an Overnight Energy Crash—and the Science Behind It

There’s a specific kind of frustration that can hit in midlife—you’re doing all the “right” things, yet your body suddenly feels like it did a 180 and forgot to tell you. Your energy, sleep gets weird, and your brain has a fog as thick as pea soup.

While it’s easy to assume you’re lazy, stressed, or somehow failing at aging gracefully, this episode of Over 50 & Flourishing offers a different explanation. Host Dominique Sachse sits down with physician and longevity researcher, Dr. Andrew Salzman, to unpack NAD, a molecule involved in cellular energy production, repair, and overall function…and perhaps the one thing you’ve been missing in your wellness routine.

Why NAD declines with age

If you’ve never heard of NAD before, you’re not alone. It’s one of those health terms that sounds highly technical until you realize it may be tied to issues plenty of people complain about every day. 

In simple terms, NAD is a molecule the body uses to help create cellular energy and support repair processes. Dr. Salzman calls it “the quintessential molecule for our health,” adding that it’s involved in hundreds of functions throughout the body.

So why does it drop with age? According to Salzman, part of the issue is that the body begins producing more of an enzyme called CD38 over time. He describes CD38 as a major culprit in aging because it “cuts, it cleaves, and destroys” NAD. In other words, your body is still trying to make what it needs, but it may also be breaking more of it down as the years go on.

And it might not be obvious at first. In your 30s or 40s, you might just notice needing more recovery time or wondering why your energy feels less consistent. Then one day you’re staring at your third coffee like it personally betrayed you. “By the time you’re 60, 70, you have half the NAD that you had as a youngster,” Dr. Salzman notes, offering a valid explanation for the excessive yawns.

How it may relate to fatigue and brain fog

If you’ve ever had the thought, Why do I feel tired even when I technically rested?—listen up.

According to Dr. Salzman, NAD plays a central role in helping the body produce ATP, which he describes as the body’s energy currency. ATP powers everyday functions, from movement to digestion to mental focus. If NAD levels decline, the body may become less efficient at making that energy supply.

“Without NAD you simply cannot make any ATP at all,” he explains. That doesn’t mean low NAD is the sole reason someone feels exhausted, but it may be one factor in why energy can feel less steady with age.

And the same conversation extends to mental clarity. Dr. Salzman notes that NAD is present in the brain and supports the processes required for thinking and complex tasks. He also ties energy delivery to memory and focus, saying, “Memory requires massive amounts of energy to make a memory, so you don’t store your memories as well.”

In real life, this can show up less dramatically than people expect. It may look like walking into a room and forgetting why, rereading the same email three times, or losing your train of thought mid-sentence and hoping it circles back. Either way, it’s a total pain.

Hair, skin, libido, and blood pressure links

If aging has started to show up in places that feel oddly specific, like thinning hair, drier skin, lower libido, or a blood pressure reading that suddenly gets your attention, cellular energy may be part of the picture.

Dr. Salzman connects lower NAD levels to changes in the hair follicle and skin. He says NAD declines can contribute to reduced collagen and elastin, which may affect skin firmness and texture over time. He also links lower NAD to hair changes, explaining that follicles may become less efficient, potentially leading to graying and thinning.

Then there’s libido, a topic many women care about and fewer people explain clearly. He says NAD helps support the production of nitric oxide, a compound involved in circulation and sexual response. As NAD levels fall, he suggests nitric oxide production may decline as well, which can influence arousal and overall sexual health.

He also ties that same nitric oxide pathway to vascular tone and blood pressure, noting that lower levels may play a role in rising blood pressure as people age.

Lifestyle habits that support NAD naturally

Before adding another expensive supplement bottle to your routine, Dr. Salzman makes a strong case for basics first: “In all respects, exercise, I think, is the number one thing that one can do, one can choose to do. That has a decisive impact on their overall health.”

He specifically recommends forms of cardiovascular exercise that raise the heart rate. Don’t waste time trying to find the perfect workout; just find one one you’ll actually do and stay committed to—even if it’s just walking.

Nutrition matters too, especially when it comes to gut health. Dr. Salzman says, “You want to have fiber,” pointing to foods like rice, oats, vegetables, legumes, and lentils that may help beneficial gut bacteria thrive. He also warns that sugar can shift that balance the other way: “They just flourish,” he says of less helpful bacteria. 

He also emphasizes human connection, noting that isolation in older adults can have “profound medical consequences.”

What to know before buying supplements

If you already have twelve tabs open comparing different NAD products, slow down. Not all forms are created equal, and more marketing does not automatically mean more science.

Dr. Salzman explains that taking NAD itself in pill form may not be the most effective route, saying, “it’s a waste of time to take a pill of NAD because nothing will get absorbed.” Instead, he says many products focus on precursor ingredients such as NMN or NR, which the body may use to help make NAD.

He also pushes back on the growing popularity of IV NAD infusions. “I don’t know if it would hurt them, but I don’t see how it would be a direct benefit,” he says, explaining that NAD in the bloodstream may not easily enter cells the same way its precursors can.

Safety-wise, Salzman notes NMN has generally appeared well tolerated in studies discussed on the episode, but that doesn’t mean every product on the market is equal in quality, dosage, or testing standards.

If you are considering a supplement, however, do your due diligence. Check the ingredient form, dosage, third-party testing, and whether claims sound realistic. If a bottle promises to reverse aging quickly, keep looking.

And as always, talk with a healthcare provider first, especially if you take medications or have underlying health conditions. 

To hear the full conversation about NAD, listen to Over 50 & Flourishing wherever you get your podcasts.

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