In mice, a clock-related protein in certain hormone cells turns on at night, and this timing shifts when a specific receptor is missing — meaning the body might fine-tune its internal clock after genes are read.

Mice that are missing a certain brain signaling system have their daily body clock in the thyroid gland running about 5 hours earlier than normal mice — this suggests that the signaling system helps set the clock in that organ.

Mice that are missing a certain brain signaling system have weaker daily rhythms in their thyroid gland, which suggests this system helps keep the body's internal clock running strongly in that organ.

Even when the brain's main body clock loses its rhythm, the thyroid gland in mice can still keep its own daily rhythm going — suggesting it doesn’t completely depend on signals from the brain’s clock center.