I wonder if a similar technique could be used for Melatonin in saliva so that noninvasive circadian phase testing could be performed outside of the lab.

I'm convinced that if we actually looked at the circadian phase of the general population more closely we'd find A LOT of people with wonky clocks [1][2].

I've come to realize in recent months that I'm rocking a ~3h phase advance. Not terrible but it can sometimes make getting enough total sleep time challenging (bright light therapy in evenings really helps).

1. https://www.sydney.edu.au/news-opinion/news/2025/07/16/depre...

2. Circadian Genes, Rhythms, and the Biology of Bipolar Disorder - https://www.youtube.com/watch?v=eSL5hC8bzcU