Knowing how and when your mind and body work the best Is the key to unlocking ultimate efficiency. Quite simply, If you're someone who deprived himself of sleep for multiple nights in a row or random bursts of work, you should know or observe exactly at what "conditions" or time from your previous sleep(when you last woke up) IS your mind working at an optimum level and your higher cognitive functioning is thriving. Observe that. Note that. Use that information and EXPLOIT it. For me personally my mind needs to tire itself a bit, get warmed up with some daily activities and regular bustling environment. The highest level of my functioning begins about 16 hours from the time I woke up. It lasts for about 3 hours until my mind decides to shut. These 3 golden hours are where I came up with ideas, solutions and even discovered problems In my existing plans. When your mind and body is at its maximum potential, you will get important things done at a much faster rate. Knowing exactly when, makes you deadlier than ever.