The body produces the hormone melatonin in several places, mostly in the pineal gland and the eyes. It is also produced in the gastrointestinal tract, bone marrow, skin, and white blood cells known as lymphocytes. Melatonin coordinates circadian rhythms and helps induce sleep. Research suggests the decline in melatonin levels that occurs during aging contributes to insomnia and other aging-associated conditions.

Melatonin does more than assist in balancing our circadian rhythms. New research substantiates that it helps our vision.

Glaucoma/Eye Pressure

Intraocular pressure is usually lowest at night, which is also when natural melatonin levels are near their highest in the circadian cycle. IOP is highest in the morning when melatonin is low. There seems to be a correlation between IOP and melatonin; supplementing with melatonin may lower IOP.¹ While most melatonin is created in the pineal gland, certain structures within the eyes synthesize melatonin. The cells of the ciliary body, which produce aqueous humor, contain receptors activated by melatonin.² Melatonin improves the function of retinal ganglia, and in clinical research, researchers have discovered that personalized strategies for dosages are not only effective in maximizing the benefits. They also found that melatonin has benefits for sleep and circadian rhythms, especially for people with advanced glaucoma.³

Macular Degeneration

Researchers found that a combination of melatonin, zinc, and selenium, taken before bedtime, helped stabilize AMD with some remarkable improvement in the fundus of the eye after taking the combination for six months.^4 5

Researchers have established that one of the causes of macular deterioration in AMD is due to poor mitochondrial respiration.  A recent study found that melatonin’s beneficial effect on mitochondrial function reduces oxidative stress, inflammation, and cell death in the retina.⁶

With respect to the link between vision and circadian rhythms, the eye is the primary recipient of circadian signals, and because melatonin regulates circadian rhythms, its benefits are noted in the retina as well. There are several mechanisms where melatonin plays a role: in mitochondrial function, where it behaves like a mitochondria-targeted antioxidant, and in supporting the integrity of telomeres which can be damaged by oxidative stress.  Telomeres are protective structures (formed from DNA and proteins) that are found at the end of chromosomes and are required for cell division.⁷