When the clocks go backward an hour, it can disrupt the body's natural circadian rhythm – a process that governs our sleep schedule and hormone regulation. As a result, we may find it difficult to go to bed and wake up at our usual times for a while as we try to adjust. Altering your bedtime routine by 15-minute chunks gradually can help you to counteract this, as can sticking to a strict wake-up schedule and using vitamin D supplements can help to prevent fatigue.