It’s no accident that we spend a third of our lives asleep. It is essential to our health, and even animals for whom resting is complicated – such as aquatic mammals that need to surface to breathe, or birds that go up to 10 days without touching dry land – manage to sleep with surprising adaptations.
But while we sleep, the tens of trillions of microorganisms that live within us – known as the microbiota – follow their own rhythms. This microscopic colony, composed mainly of bacteria, can weigh as much as 200g. Together with its host, it forms a biological unit known as the holobiont.
