Lactose
Lactose (C12H22O11) is a form of sugar and carbohydrate that was found in milk. It consists of galactose and glucose.

Captain Jean-Luc Picard's aunt  had a recipe for a steamed hot milk toddy, which Picard shared with Doctor Crusher. She in turn prescribed one to Commander Riker, explaining that the lactose in the beverage would help him sleep better. ()

See also
 Fructose
 Glucose aka Dextrose
 Sucrose

External link
 
Biochemical compounds