In 2021, Purdue University researchers measured the effect of dark mode on smartphones with OLED screens, whose black pixels switch off. At full brightness, it cut power use by 39 to 47% on average. But at 30 to 50% brightness, a typical indoor setting, the saving dropped to just 3 to 9%. If you really want your battery to last, turning the brightness down matters far more.
Chlorine on its own is fairly gentle. But when it combines with urine, sweat and other grime from swimmers, it forms chloramines, which cause stinging eyes and that classic 'chlorine smell'. A well-kept pool barely smells at all. Shower before you swim and never pee in the water.
Muscle mass slowly shrinks with age, putting independence at risk. But in 1990, a study had nursing home residents aged 86 to 96 train their legs for eight weeks: their strength more than doubled. Muscle responds to training at any age. Getting up from a chair without using your hands is already an exercise.