Since red has the slowest vibratory rate and and longest wavelength, it stimulates adrenal glands, boosting energy.
The color indigo stimulates the brain’s pineal gland, which is the regulator of sleep patterns. Indigo also helps to free the mind of worries, fear and inhibition.
Yellow lightwaves stimulate the brain, making you alert, clearheaded and decisive. And since we associate yellow with the sun’s rays and daylight, it’s said to help us feel more optimistic.
Blue triggers the production of melotonin, a brain chemical that helps us relax and sleep soundly. Blue also stimulates the thyroid gland to release thyroxin, a hormone that regulates metabolic rate.
Green affects the nervous system, making us breathe slowly and deeply, slowing the production of stress hormones and helping the heart relax.
Orange strengthens the immune system and the lungs, which can ward off spring allergies. Orange also has a strong beneficial effect on the digestive system and can stimulate the sexual organs.
Violet cools us, alleviating “hot” conditions like heat rash and sunburn, and suppressing hunger and balancing metabolism. It also stimulates the pituitary gland, the part of the brain that releases tension-fighting beta-endorphins.
(source: ©Society of American Florists)