2026-02-10 14:26:20

People turning 40 have also approached the most exhausting decade of life.

Professor Michelle Spear, an anatomist at the University of Bristol, says midlife fatigue is caused by a perfect storm of small physical changes colliding with peak life pressures.

Careers intensify, family responsibilities pile up and, at the same time, the body quietly becomes less forgiving.

She explained that midlife tiredness is best seen as a “mismatch between biology and demand”.

Professor Spear added to the Daily Mail: “Our bodies are still perfectly capable of producing energy, but they do so under different conditions than in earlier adulthood, while the demands placed on that energy often peak.”

In your 20s, the body runs efficiently. Muscles repair quickly, inflammation settles fast and energy-producing mitochondria work at full throttle.

Professor Spear continued: “When you have more available energy, everything costs less. Poor sleep, a late night, or intense exercise simply has fewer consequences.”

By the late 30s and early 40s, that balance begins to shift. Muscle mass naturally declines unless actively maintained, meaning everyday movements require more effort.

At the same time, mitochondria become less efficient, producing more biological “waste” that makes recovery harder.

Sleep also takes a hit. Hormonal changes – particularly for women during perimenopause – disrupt deep, restorative sleep.

Professor Spear said: “This makes it harder to stay in slow-wave, restorative sleep.”

Rising night-time cortisol levels mean people wake feeling unrefreshed, even after a full night in bed.

Crucially, this all happens just as mental load peaks. Studies show midlife brings maximum cognitive and emotional strain, with leadership roles, multitasking and caregiving all draining energy as effectively as physical labour.

However, the exhaustion doesn’t last forever. Energy levels often stabilise in the 60s as stress reduces and sleep patterns improve. With regular strength training, mitochondria can even regain efficiency.

Professor Spear said: “The goal isn’t to recreate 20-year-old energy. It’s to protect recovery – through consistent sleep, resistance exercise, stress management and adequate protein.”

Visit Bang Bizarre (main website)