The Hare + The Moon Apothecary - Moonlight Sleepy Spray, 50ml. Deep sleep is essential for the human body to get fully rested, heal wounds, regenerate, and preserve enough energy to function correctly the next day. Essential oils are also known to work through the olfactory system to cause the brain to secrete neurotransmitters, such as dopamine and serotonin, which can elevate mood. These neurotransmitters are needed to make you feel calm and relaxed, but serotonin is also required to produce melatonin, the hormone responsible for making you sleepy at bedtime.