Persistent fatigue affects thousands across the UK, leaving many feeling 'dog tired' despite getting enough sleep. But what's behind this exhausting phenomenon? Experts are now revealing surprising factors contributing to energy drain, from indoor air pollution to dietary habits and even our approach to rest.
One often-overlooked culprit is poor bedroom ventilation. Dr Jemma King warns that a closed room with a partner and heating can see carbon dioxide (CO2) levels rise significantly by 3am, potentially reaching 1,500 to 2,500 parts per million (ppm). Research indicates that CO2 levels above 1,000 ppm can decrease sleep efficiency, reduce deep sleep, and increase salivary cortisol upon waking. Opening a window, even slightly, can make all the difference.
Beyond environmental factors, biochemical processes play a significant role. Justin Roberts, Professor of Nutritional Physiology at Anglia Ruskin University, explains that our energy comes from adenosine triphosphate (ATP) molecules produced by mitochondria. As we age, mitochondrial numbers decline, affecting ATP production. Creatine can help regenerate ATP and research consistently shows benefits for older adults, regular exercisers, women, vegans, and vegetarians. Supplementing with 3-5g of micronised creatine monohydrate daily for two to four weeks, followed by a break, can improve mental fatigue, reduce exercise-induced fatigue, and enhance mood and cognitive function after poor sleep.
Our connection to the outdoors also impacts our energy. Dr Brendan Gabriel's research at the University of Aberdeen suggests that daylight exposure improves sleep and blood sugar control, linked to our circadian rhythms. Regular outdoor daylight exposure helps our body differentiate between day and night, leading to better sleep quality.
Dietary deficiencies are another significant contributor. Research Fellow Dr Emily Leeming notes that a staggering 96% of people in the UK do not meet the recommended daily fibre intake of at least 30g. Fibre-rich meals can slow sugar release into the bloodstream, providing more sustained energy. Dr Leeming advocates for incorporating 'BGBGs'—beans, greens, berries, grains, seeds, and nuts—as a foundation of meals to boost fibre intake. A lack of polyphenols, antioxidants found in colourful fruits and vegetables, can contribute to fatigue and brain fog.