PTH and Hypercalcemia: Indeed, a proof‐of‐principle study demonstrated that treatment of osteoporotic rats with vitamin D at the start of the dark phase instead of the light phase is not only more effective but also results into fewer side effects, such as hypercalcemia.(135) This thus indicates that chronotherapy is a promising strategy to reduce or prevent adverse effects associated with osteoporosis treatment in humans, such as hypercalcemia‐induced dizziness and leg cramps in the case of PTH treatment.(69)