Suddenly, the oldest health advice begins to make much more sense. Exercise doesn\u2019t simply boost muscle mass, it bulks up<\/a> the hippocampus \u2013 a key region of the brain involved in learning and memory. It also encourages mitochondria to become more numerous and more efficient<\/a>. We often imagine we\u2019re training our bodies; we\u2019re also strengthening<\/a> the ancient energy system that allows our brains to work.<\/p>\n Sleep performs a different kind of maintenance. While we\u2019re unconscious, the brain is astonishingly busy. Memories are consolidated and worn-out cellular components \u2013 including mitochondria \u2013 are repaired or replaced<\/a>. So rather than thinking of sleep as simply rest, we can conceive of it, at least partly, as a mitochondrial maintenance shift, aimed at preparing the brain for another day of active learning, adapting and imagining.<\/p>\n Then there\u2019s food. Mitochondria rely entirely on what we eat to perform their remarkable chemistry. The quality of that fuel matters. Diets rich in minimally processed foods<\/a> provide the ingredients for efficient energy transformation, while diets that continually overwhelm the system appear to make that process less efficient<\/a> over time.<\/p>\n Seen through this lens, sleep, exercise and diet stop looking like three separate pieces of lifestyle advice and become different ways of caring for the same biological inheritance. What fascinates me most is that this new understanding reaches far beyond physical health. Scientists are uncovering intriguing links<\/a> between mitochondrial function and resilience, mood<\/a>, personality<\/a> traits, and even our social lives<\/a>.<\/p>\n For centuries we\u2019ve tended to separate mind from body, as though thoughts somehow floated free of the flesh that produced them. The reality is that thoughts emerge from living tissue that must constantly capture, transform and use energy simply to exist.<\/p>\n The mitochondrial psychobiologist Martin Picard has argued that we\u2019ve become accustomed to thinking of ourselves as molecular machines, when it may be more useful to think of ourselves as energetic processes<\/a>. The brain is an organ whose every thought, memory and feeling depends on the continuous transformation of energy within billions of cells.<\/p>\n skip past newsletter promotion<\/a><\/p>\n Sign up to Bookmarks<\/p>\n Discover new books and learn more about your favourite authors with our expert reviews, interviews and news stories. Literary delights delivered direct to you<\/p>\n after newsletter promotion<\/p>\n Seen this way, sleep is no longer simply rest, and exercise is no longer simply fitness. Food is no longer simply fuel. They\u2019re different ways of sustaining the ancient biological partnership that allows our bodies \u2013 and our minds \u2013 to flourish.<\/p>\n It\u2019s remarkable to think that every idea you\u2019ve ever had, every problem you\u2019ve solved, every person you\u2019ve loved and every hope you\u2019ve held has depended upon an alliance forged more than 2bn years ago. The tiny descendants of that ancient bacterium have been quietly working inside us ever since, making possible not just movement or metabolism but thought itself.<\/p>\n Perhaps that\u2019s why the oldest health advice has survived every new scientific fashion. Long before we knew about ATP, oxidative phosphorylation or mitochondria, we recognised that people who slept well, moved regularly and ate nourishing food tended to flourish. We\u2019re finally beginning to understand why.<\/p>\n Hannah Critchlow is a neuroscientist and author of The 21st Century Brain<\/a> (Torva).<\/p>\n Further reading<\/p>\n The Song of the Cell<\/a> by Siddhartha Mukherjee (Vintage, \u00a314.99)<\/p>\n Transformer<\/a>: The Deep Chemistry of Life and Death by Nick Lane (Profile, \u00a314.99<\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/ie\/wp-content\/uploads\/2026\/07\/1784087591_428_500.jpg\")
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