The evidence that humans would naturally be designed to sleep “multiple times a day” is quite mixed. “Multiple” does a lot of heavy lifting here, when basically most evidence points to two batches, following either of these patterns:

- a long uninterrupted night cycle and a short (20-60 mins) afternoon nap. Around 2pm. - a night cycle split into two halves. With a 1-2h break (maybe up to 3h) starting around midnight to 2am.

The former is still very common, and imho stretching the definition of multiple cycles. The latter is more historical (more common when there are long winter nights and no electricity).

Also making it a “Western” problem is kinda weird? There are other cultures where single cycle sleep has existed. Even hunter-gatherer groups with little to no contact with the west. And alternatively afternoon naps are still quite common is some western areas. I guess the main thing that prevent it would be the classic work day schedule.