Chamomile tea
From Memory Alpha, the free Star Trek reference.
Chamomile tea, a Human beverage, is a tea made from the flower of the chamomile plant found on Earth native to Egypt. Noted for its calming properties, it is often considered a sleeping aid in many Terran cultures.
During the 22nd century, Subcommander T'Pol occasionally enjoyed a cup of chamomile tea. (ENT: "Fusion")
