Modern life promotes an easy, indoor existence, living under artificial light and glued to glowing screens delivering constant dopamine hits. This runs counter to human biology, which is deeply tuned to the natural rhythms of light and dark. Living by the light means embracing safe daily sun exposure, while protecting darkness at night offers powerful benefits that strengthen both physical and mental resilience.

Force of Nature – The Sun

Most of us by now know that sunlight triggers vitamin D synthesis in the skin. This is essential for maintaining strong bone density, a robust immune system and muscle mass. This is all essential if you want to thrive through and after service. Holick et al.’s research shows that sufficient vitamin D levels reduce the risk of osteoporosis, respiratory infections and all-cause mortality.

Beyond vitamin D, exposure to natural light plays a critical role in regulating our circadian rhythm, the internal 24-hour clock that governs sleep, hormones, metabolism, and mood. Morning light exposure improves alertness, cognitive performance and emotional wellbeing. Importantly, it can also reduce the symptoms of depression and seasonal affective disorder. Importantly, ‘safe’ sun exposure means short, regular periods outdoors, avoiding sunburn.

Sleep - Love the Dark

Just as daylight is essential during the day, darkness is essential at night. Good sleep hygiene helps align our biology with natural light–dark cycles. One of the most important habits is avoiding blue light from screens for at least one hour before bed. Chang et al.’s work shows that blue light suppresses melatonin, delays sleep onset and reduces sleep quality.

Your sleep environment is also critical. A tidy, clutter-free bedroom reduces cognitive arousal and stress, making it easier to relax. A cool room, generally around 18–20 °C supports the natural drop in core body temperature required for deep sleep. Finally, sufficient sleep duration (typically 7–9 hours for adults) is numero uno when it comes to good health. Chronic sleep restriction is associated with impaired immunity, metabolic dysfunction, cardiovascular disease and reduced mental health.