Liberation from daily life can turn on-the-road slumber into a profound experience.

The hottest hours in Alter do Chão, a Brazilian town in the Amazon region, are after lunch. The dogs disappear, the shops shutter. Every now and again a humid breeze stirs the palms overhead, which rustle like dry silk. Suspended in midair I sigh, stretch, adjust position in my hammock. As I swing this cotton cocoon into a gentle rhythm, my mind begins to hum a line from an Amazon poem: "Everything important happens in a hammock." I don't know who wrote it, but I wish I did. That poet understands perfectly why I will travel thousands of miles just to take a nap.

Sleeping is one of my deepest travel pleasures, but I don't talk about it very much because I feel a little guilty. When friends share details of their intricately planned trips, in which every second of precious travel time is pencilled in with activities, meals, museums, and mountain treks, I smile encouragingly and don't say much. What would they think if they knew that my own travel itineraries include yawningly empty slots for late afternoon naps under staccato Caribbean downpours and lazy mornings nestled between monogrammed Italian linens?

Better sleep is one of travel's happy side effects. When I visited Mexico's Yucatán coast in my early 20s, I was shocked by how many hours—more than 12—I spent sleeping most days. And I wasn't staying in a comfy, hermetically sealed resort; I paid $3 a night to hang a hammock with 20 other backpackers under a thatched roof in a group hostel. There were lots of fussy roosters in the neighboring lot, but it didn't matter. Far from home and from my own bed, surrounded by strange smells and sounds, I could plunge into a sleep that was more profound, dream-filled, and enjoyable than I imagined possible.

Liberated from alarm clocks and responsibilities, sleep flows more easily. But I don't think simple de-stressing explains why the quality and texture of travel sleep is so dramatically different. My theory is that sleep is actually an extension of our travels, not a pause or respite from them. When traveling, we open ourselves to novel sights, sounds, smells, and ways of being.New and unfamiliar stuff pours into us—cultures, music, landscapes, even ways of moving through space. It is when sleeping that we wade through this overwhelming river of stimuli. No wonder, then, that sleep becomes so much more intense when we are on the road.