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Published on: 5/5/2026
Feeling more tired after 40 is very common due to declines in NAD+, mitochondrial efficiency and hormone shifts, all of which sap cellular energy. Working with your doctor to run targeted tests and build a personalized plan of lifestyle, supplement and medical strategies can help reignite your natural energy production.
There are multiple assessments—from blood panels for vitamins, hormones and NAD+ precursors to checks for anemia and thyroid function—as well as nutrition, exercise, sleep and stress-reduction tactics to consider. See below for important details that will guide your next steps.
Feeling more tired than you used to after 40 is common—and you're not alone. As we age, key molecules like NAD+ decline, leading to lower energy levels after 40, slower recovery, and that all-too-familiar "drag" in the afternoon. The good news: working with your doctor and making targeted lifestyle changes can help reignite your natural energy production. Here's how to start the conversation and build a plan tailored to you.
Understanding these changes helps you see why a one-size-fits-all energy drink won't solve the problem—and why medical guidance matters.
Before you book an appointment, gather the following:
Having this information ready lets your doctor tailor tests and recommendations to your unique situation.
Discuss these with your doctor to get a full picture of what's behind your fatigue:
Working with your doctor, you can pair medical treatments with daily habits that naturally support NAD+ production and mitochondrial function:
When lifestyle tweaks aren't enough, your doctor may discuss targeted supplements and therapies:
While most energy loss after 40 is benign and reversible, some signs warrant urgent medical attention. If you're experiencing concerning symptoms but aren't sure whether they require immediate care, you can start by using this free Medically approved LLM Symptom Checker Chat Bot to help guide your next steps. Seek immediate medical attention if you experience:
Restoring youthful energy is a journey, not a quick fix. By combining:
you and your doctor can craft a sustainable plan that addresses root causes, supports healthy NAD+ levels, and keeps your energy levels after 40 thriving.
Final Reminder: Always speak to your doctor about strategies or supplements, especially if you have chronic conditions or take medications. For any life-threatening or serious symptoms, call emergency services or seek immediate medical care.
(References)
* Sun N, Liu N, Tang Y, Han X, Li B. Mitochondrial dysfunction and its role in age-related diseases. Clin Chim Acta. 2020 Jul;506:178-187. PMID: 32677169.
* Fiuza-Luces C, Santos-Lozano A, Ramos-Barrera C, Sanchis-Gomar F, Fogelholm M, Lucia A. Strategies to Combat Age-Related Decline in Physical Activity and Energy Expenditure. J Appl Physiol (1985). 2020 Apr 1;128(4):1042-1051. PMID: 32066897.
* Valdivieso-Garcia A, Funes P, Fuentes-Silva C, Garcia-Heredia B, Solas M, Ramirez MJ, San-Juan-Vergara A. The impact of aging on mitochondrial metabolism: a comprehensive review. Exp Gerontol. 2022 Jan;157:111624. PMID: 35058697.
* Landi F, Calvani R, Stella F, Cesari M, Tosato M, Martone AM, Cherubini A, Corsonello A, Di Bari M, Onder G, Marzetti E. Nutritional Interventions to Combat Age-Related Muscle Loss (Sarcopenia) and Improve Physical Function: A Systematic Review. Nutrients. 2021 Mar 22;13(3):1018. PMID: 33762699.
* Nunan D, Elphick L, Al-Khudairy L, Marshall F, Salciccioli J, Al-Mohammad A, Banerjee A, Rajkumar C. Exercise and physical activity in older adults: An updated narrative review. Age Ageing. 2023 Feb 22;52(2):afad033. PMID: 36814925.
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