What makes you feel rested? It is an interesting question, an interesting and very human concept. We do not know if hibernation or seasonal change allow other organisms to rest. My dog sleeps about twenty hours a day - it is hard to believe she needs this much 'rest'. People are often aware of needing rest, less often of being well-rested. We cannot sustain continuous activity for very long and yet we often wake feeling less than rested. What's up?
Your best source of information about the rest you need is you. You probably have many strategies for being tired and needing rest. As you think about them, you can sort out the kind of tired that comes from physical activity, the kind that comes from thinking of too much information, the kind that results from powerful, and powerfully mixed, feelings. Since none of these is a situation that can be avoided, you need to look from here to the times when you have rested effectively.
Trace a time when you were tired and follow it until you are no longer aware of needing rest. What happened in the middle? Did you become aware of being rested or did you just stop being aware that you were tired? You can notice different kinds of rest: the best rest you have had this week, the best rest you have ever had, the rest that preceded or followed an extraordinary burst of productivity.
You may have fallen asleep exhausted only to wake up too early, tense with whatever was unresolved when you went to sleep? You may have gone days and nights in a consistent pattern, comforted as much by the routine as by the sleep. You may even have gone weeks at a time on much less sleep than you are sure you "need" and yet been extremely productive and happy. Only you have access to your patterns of stress and rest.
Use those patterns. Trust them. They are as unique as a fingerprint and as you begin to notice their details, you will begin to notice that it is hard to focus on the need for rest. It is much easier to focus on the need for engagement, for connection, for achievement. As you focus on those needs, you might find yourself automatically programming the precise amount of rest you need in order to thoroughly engage in what you really want.