In a body asleep, not all is at rest.  The heart still beats, the lungs expand and contract, the blood circulates through elastic arteries, the brain still functions in a semi-conscious state, dreams are created, the organs do their thing, even the reticular formation is alert to possible signs of danger.

This activity of living creatures brings to mind certain cities (not the real big ones that never seem to sleep) but smaller ones where street lights still burn, water and sewerage still flow through pipes, police stations remain functioning to respond to danger, radio stations and TV stations send shows through wires or through the air, airports welcome planes along with the visitors they hold, lovers still copulate, crimes are still committed, the insomnias still roam their rooms, heating systems and air-conditioners respond to thermostats by pumping and blowing.  And throughout the physical space of the city electromagnetic radiation carries countless messages, neutrinos pass in infinite numbers through everything solid disturbing nothing molecular or atomic, while gravity and friction hold everything in place.

Although the city slumbers and darkens, its sleep is like the sleep of its many residents; mostly stilled but still functioning internally:  rapid eye movement belies the quieted brain, the breath is slowed, internal gases are released beneath the covers, and the bed creaks in response to the occasional semi-conscious turn of the body.  So sleeps the city — so sleep the creatures in their bedrooms, nests, and burrows.