What Melatonin is

Class and mechanism

Melatonin is a pineal hormone. The hormone secreted by the pineal gland in response to darkness, acting at MT1 and MT2 receptors as the principal circadian timing signal.

Where it sits

Ancillary compounds sit alongside a primary compound rather than replacing it. They are usually pharmaceutical products with long established use outside this context.

Others in the ancillary compounds range

Melatonin sits in the ancillary compounds group. The compounds below share that grouping, which is the useful starting point when comparing one against another: same group means the comparison is like for like, different group usually means it is not.