Bodies need rest too. Time is required for healing, for building up reserves and for gaining a renewed perspective. Sometimes, rest means to stop being active for a while. Sometimes, rest is not a cessation of activity, but a change of activity. In the US, we call this kind of rest a "vacation."
And a cessation of activity does not necessarily mean "a cessation of activity." Sleep is, for all purposes, a regular, voluntary cessation of activity. But research shows that sleep has cycles, involving varying degrees of activity. People progress through stages of less and less physical activity, until they reach a stage called "REM sleep." REM sleep is characterized by the least amount of physical activity, but also a sudden upsurge of mental activity. It is the stage when dreams happen. Scientists still don't fully understand dreams. A person seems somehow to process recent events while dreaming. Sometimes, scientists see more mental activity during REM sleep than when the person is awake.
People need the right kind of rest too. Restoration of some reserves, in the form of the manufacture of some hormones by the body, take place after 75-80% of the entire sleep cycle. (Meaning it occurs after 6-7 hours of continuous sleep.) So, if we don't get enough sleep, or we get interrupted sleep, these reserves are not manufactured, and it could be detrimental to our health over the long haul.
There are some similarities between physical and spiritual rest. Both provide healing and restoration. With spiritual rest, a person is removed from the "war." There is a release from stresses. There is a renewal of perspectives and expectations. It will bring peace.
Now, as one person put it, "sometimes, the most spiritual thing you can do is take a nap." There is a crossover between physical rest and spiritual rest. Sometimes, to get spiritual rest, we need physical rest.
But, there is also true spiritual rest. We discussed the spiritual disciplines as part of getting exercise. The disciplines can also be part of getting rest. They can challenge our thinking and force to change our world view -- thus forcing us to move, to become stronger, to change, to exercise. They can also uncover truths that comfort, encourage, heal and restore -- in other words, provide rest.
There are also spiritual "vacations." They go by various names. Conferences and retreats are the most common. There are also walks, camps, and connects to name a few. No matter the name, a person removes himself from normal concerns and impending crises to give himself exclusively to his relationship with God and, possibly, God's family. He takes the time to put the clutter of life in a box (no doubt, to pull it all out again at a later time) and to review, clarify and prioritize what is important in life. And this might not be done in an overt manner.
No sane person would consider going weeks without sleep. So, every child of God ought to provide opportunity for regular rest, and probably, include both varieties,