In a groundbreaking discovery, Chinese scientists have unraveled the mysteries of our biological clock, shedding light on why we wake up and eat at specific times each day and why we naturally feel sleepy at night. Contrary to the conventional belief of an invisible biological clock, researchers have identified a "tangible hand" in the form of primary cilia within SCN neurons. These primary cilia act as antenna-like structures, extending from the cell membrane. Remarkably, these cilia undergo rhythmic changes every 24 hours, playing a crucial role in mediating the Sonic Hedgehog (SHH) signaling. This signaling allows cells within the master circadian clock to synchronize and control our circadian rhythmicity. "The biological clock was previously thought to be an invisible clock, while this time we found that the antennae-like primary cilia sticking out of the cell surface show rhythmic changes, indicating that the biological clock is a tangible and visual internal clock," explained Li Huiyan, a researcher at the PLA Academy
