In healthy mice who were kept in normal 12-hour, alternating light-dark cycles, the team took samples every six hours for two full days. During the dark phase, the bacteria in these nocturnal mice were busy digesting nutrients, repairing their DNA, and growing, Science reports. Microbes did their housekeeping during the light phase: detoxifying, sensing chemicals, and building the tails that help them move.

Gut bacteria in mutant mice with disabled inner clocks didn’t exhibit the same fluctuations in response to either light or dark cycles. But when these bacteria were transplanted into normal mice, the microbes began to show normal rhythms within a week, suggests that the mouse clock controls that of the bacteria, Science explains.

All this time I thought it was the microbiome CAUSING the feelings of jet lag.

Whereas it sounds like the microbiome is controlled by -- and reacts to -- the body's internal clock.