During deep sleep, the hippocampus 'replays' what you learned during the day and transfers those memories to the cortex, where they stabilise. Pulling an all-nighter before an exam sabotages this consolidation. It's better to review in the evening and then get a full night's sleep. Sleep is part of learning, not a competitor to it.
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.