There are many mysteries in science. What is dark matter? Why are we conscious? Are we alone in the universe? But none looms larger in the mind of the average adult than this: why am I so exhausted all the time?
It is a crucial question, not least because, according to a recent analysis of data from 32 countries, as many as 1 in 5 otherwise healthy adults complain of problematic levels of fatigue. Feeling tired all the time is one of the most common reasons to seek medical attention – so much so, in fact, that medical professionals commonly abbreviate it to TATT, perhaps to save their own energy. Often, there is no obvious medical explanation for what is causing the fatigue and not much the doctor can offer beyond blood tests to rule out any obvious deficiencies.
Despite this huge burden on our collective well-being, the question of what it means to “have energy” had, until recently, attracted surprisingly little medical research. Into the void stepped the trillion-dollar wellness industry, offering no end of ways to boost our vigour with various supplements, diets and lifestyle hacks.
Now, though, scientists are taking a fresh look at what it means to feel energised – or not – and the research is revealing that how we perceive this state largely hinges on the brain’s ongoing assessment of how much energy is available to our cells. This discovery is changing how we think about our general health, opening up possible new avenues to treat clinical levels of fatigue, and…
Article amended on 13 March 2025
We corrected the affiliations for Lisa Feldman Barrett and Elissa Epel
