THAT'S THE WHY:THE CLOCK on the wall has an important role in organising our days and nights, but did you know that you have an internal clock too?

It’s a complex mechanism that involves various ‘clock’ genes and signalling systems in the body and its light/dark cycles play an important role in regulating it.

In recent years, evidence has been growing that disrupting our internal or ‘circadian’ body clock is linked with a negative impact on health.

It’s a complex area, but a new study has been looking at some clues from zebrafish. It found that disrupting the circadian rhythms of fish embryos had an impact on the growth of blood vessels during development – in particular a key class of molecule called VEGF was affected. VEGF plays an important role in angiogenesis, or the formation of blood vessels.

And, while it may seem like a jump, the authors reckon the results are of interest to humans too, where the production of blood vessels can be a factor in some diseases and in processes such as wound healing.

“Although the study was performed in zebrafish, our data may be reasonably extended to mammals, including humans, because the clock genes are highly conserved among these species,” they write in Cell Reports.

“These results shed mechanistic insight on the role of the circadian clock in regulation of developmental angiogenesis, and our findings may be reasonably extended to other types of physiological or pathological angiogenesis.”