Induced exhaustion is one way to test it, yes. Can't say from the article if they ruled it out. Correlation of the rest pattern with a day-night cycle does not

Induced exhaustion is one way to test it, yes. Can't say from the article if they ruled it out. Correlation of the rest pattern with a day-night cycle does not necessarily imply that the "sleep-like" state is indeed sleep, and not just a power-down low-metabolical wait-state used for the bio-chemistry to catch up after a day of activity is over.