Low Energy and Fatigue in Women After 40
What Science Shows
Many women begin to notice a decline in energy after the age of forty. It may become harder to wake up in the morning, fatigue accumulates more quickly during the day, and recovery after normal daily activities can take longer than before.
These changes are often perceived as an inevitable part of aging. However, scientific research suggests that persistent fatigue in this stage of life is rarely explained by age alone. It is more often associated with physiological changes, sleep quality, overall health, and the cumulative demands of daily life.
Understanding these mechanisms helps to place the experience of fatigue into a clearer context and allows for a more structured approach to restoring energy and wellbeing.
How common is fatigue during this stage of life
Scientific studies show that fatigue is one of the most frequently reported symptoms during the perimenopausal transition. Research indicates that approximately 67% of menopausal women report significant fatigue, which can affect both physical and psychological functioning. The prevalence of such symptoms begins to increase in the mid-forties, when the hormonal transition associated with perimenopause often begins (Chiu et al., 2021; Yong et al., 2025).
Other research has found that around 46% of women in perimenopause experience persistent physical or mental exhaustion, with prevalence increasing further after menopause (Taylor-Swanson et al., 2018).
Hormonal changes and energy levels
In many women the increase in fatigue coincides with the beginning of perimenopause, the transitional stage before menopause.
During this period ovarian function gradually changes and levels of estrogen and progesterone become less stable. These hormones influence several systems that are directly connected with energy levels, including sleep regulation, brain function, and metabolic processes.
Fluctuating hormone levels may therefore contribute to symptoms such as:
disrupted sleep
reduced concentration
mood changes
a persistent sense of physical or mental fatigue
It is important to note that hormonal fluctuations often produce stronger symptoms than a gradual hormonal decline alone.
Sleep disturbances as a major contributor
Changes in sleep quality are one of the most significant factors contributing to fatigue during this stage of life.
A large meta-analysis of studies on menopause and sleep found that sleep disorders affect around 47% of women during perimenopause and approximately 60% after menopause (Salari et al., 2023).
Women may notice difficulties such as:
problems falling asleep
frequent awakenings during the night
lighter or more fragmented sleep
early morning awakenings
Even when the total number of hours spent in bed remains similar, the restorative quality of sleep may decline. When this happens, the body does not recover fully during the night, and daytime energy levels can gradually decrease.
Lifestyle demands and accumulated stress
Physiological changes are not the only contributors to fatigue. The period between forty and fifty often coincides with high levels of professional and family responsibility. Many women are simultaneously managing demanding careers, family life, and ongoing emotional responsibilities.
Sustained psychological load and insufficient recovery can lead to cumulative fatigue over time. In addition, changes in physical activity levels and gradual shifts in body composition may also influence endurance and overall energy levels.
When fatigue may have medical causes
In some cases persistent fatigue may be related not only to lifestyle factors or hormonal changes but also to underlying medical conditions.
Low energy can sometimes be associated with:
anemia
thyroid disorders
deficiencies of iron, vitamin B12 or vitamin D
certain sleep disorders
depressive conditions
It is important to understand that such conditions cannot be diagnosed based on symptoms alone. Proper evaluation requires medical assessment and laboratory testing. If fatigue becomes persistent, severe, or progressively worse, it is advisable to discuss the symptoms with a healthcare professional. Any specific treatment for medical conditions should be prescribed by a physician.
Conclusion
A decline in energy after the age of forty is a common experience, but it should not automatically be considered an unavoidable part of life. In many cases fatigue results from a combination of hormonal changes, sleep disturbances, lifestyle demands, and health-related factors.
Scientific evidence shows that fatigue is one of the most frequently reported symptoms during the menopausal transition. With a better understanding of the underlying mechanisms and a structured approach to lifestyle and health, many women can significantly improve their energy levels and overall sense of wellbeing.
Scientific Sources
Chiu HH et al. The Perimenopausal Fatigue Self-Management Scale Is a Valid Instrument for Assessing Fatigue in Perimenopausal Women. https://pmc.ncbi.nlm.nih.gov/articles/PMC8002518/
Taylor-Swanson L et al. The Dynamics of Stress and Fatigue Across the Menopausal Transition. https://pmc.ncbi.nlm.nih.gov/articles/PMC5866170/
Yong Y et al. Prevalence and Severity of Menopausal Symptoms in Women Aged 40–60 Years. https://pmc.ncbi.nlm.nih.gov/articles/PMC11982920/
Salari N et al. Global Prevalence of Sleep Disorders During Menopause: A Systematic Review and Meta-Analysis. https://pmc.ncbi.nlm.nih.gov/articles/PMC9996569/
Shanmugan S, Epperson CN. Sleep and Brain Function at Menopause. https://pmc.ncbi.nlm.nih.gov/articles/PMC11824937/
