There is much deliberation over the species of plant called chamomile. Some believe that a similar plant, Roman or English chamomile (Chamaemelum noble), is actually the same species. German, Hungarian or blue chamomile (Matricaria recutita) produces a deep blue oil, while Chamaemelun nobile oil is pale blue to clear. The oil is distilled from the flowers.
The scent is a sedative, and helps lull the body to sleep.