Ok for this I will need more details on what that person does before they go to bed but I have a few suggestions. Before you go to bed make sure you go down a list and make sure you did everything that needed to be done that day is done; next make sure you are not forgetting to set something out that you know you were supposed to set out; lastly just relax and let your body take control and get the rest it needs and desires.
That can be taken many different ways maybe: they push themselves to hard and don’t know when to take a break or they cant settle down, sleep or, don’t know when to stop.