The best time to take a nap can also be influenced by how long you plan to be awake. If you know that you are going to stay awake for a long period of time, taking a nap prior to this period of sleep deprivation can improve your performance. These types of naps that are taken in advance of sustained wakefulness are known as Prophylactic Naps. The key to these naps is to sleep before the period of sleep deprivation. Taking prophylactic naps can help keep you alert and focused.