In the twenty-first century, we increasingly push our daily routines into the night, carrying out work, exercise and our social lives long after dark. But new science has proven that living out of sync with this clock is not only disrupting our sleep, but leaving us more vulnerable to infection, cancer, obesity, type 2 diabetes, heart disease and mental illness. In Life Time, Professor Russell Foster shares his life's work, illustrating the surprising effects the time of day can have on our health- how a walk outside at dawn can ensure a better night's sleep, how eating after sundown can affect our weight, and the extraordinary effects the time we take our medication can have on our risk of life-threatening conditions, such as strokes. In the modern world, we have neglected an essential part of our biology. But with knowledge of this astonishing science, we can get back into the rhythm, and live healthier, sharper lives.