Though it is well established that light is the primary factor regulating our body’s biological clock, it was unknown if or how physiological factors could regulate the SCN.
“Our study is the first to show that the SCN is listening to physiological signals and that such signals can in fact regulate clock time,” says Bourque.
Gizowski and Bourque were able to show that salt-sensitive neurons found in a specific region of the brain - the organum vasculosum of the lamina terminalis – are capable of activating the brain’s master circadian clock at a time of day when it is normally silent.
“This suggests that there could be ways by which we could speed up the clock, which could be useful to adapt more quickly to the time change associated with long distance travel, or when our work schedule is shifted by several hours,” explains Gizowski.
The researchers now hope to establish if natural increases in blood sodium levels – through eating - have the same effect and whether or not these also occur in humans.
“One concern is that although ingestion of small amounts of salt is pleasant and not dangerous, it can be toxic when consumed in large amounts,” Bourque adds. “Much more work is needed to examine if this finding is applicable to humans in a safe and practical way.”