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Brain and Body
Light and Air
Melatonin and its relationship to environmental therapeutics
The hormone melatonin is produced by the pineal gland which lies deep inside the brain — but it can also be introduced artificially in pill or tablet form over a wide range of doses. At medium doses, it can help you fall sleep, or nap, during the day or evening, when pineal melatonin is “off” during daytime hours. At very low doses late in the day, it can shift the circadian clock earlier without making you sleepy, while helping with sleep onset for people with late chronotypes (“owls”). At night, after pineal secretion has begun, adding melatonin has little effect, except perhaps in people who are melatonin deficient.
As a hormone of darkness, melatonin acts on the circadian rhythm of sleep in a pattern opposite to light therapy: it shifts the inner clock earlier in the late afternoon and evening and shifts it later in the morning. The two methods can be combined to strengthen clock shifts, but their effect cancels out if taken at the same time. This technique is at the vanguard of chronotherapeutics for sleep management, still a topic of research and development.
Find out more in CET’s collection of original articles and gems from the literature:
An introduction for everyone, by Josephine Arendt, PhDThe Night, and Sleep, Need Darkness
The real-life context in which we can get the best sleep, by Anna Wirz-Justice, PhDMelatonin: The darkness hormone and its uses
A free CET e-book by Josephine Arendt, PhD, covering its surprising discovery, effects on body temperature and circadian rhythms, and response to artificial supplementation.Self-assessment: The AutoMEQ and melatonin onset
Find out when your melatonin starts to rise in the evening, based on an online questionnaire that syncs with lab measurements of blood and saliva samples. How is the timing of pineal melatonin onset related to when you are ready to fall asleep?Blue-Blocking Room Light and Night Light
. . . for evening room light and nighttime visibility. By projecting light with an amber hue in the vulnerable hours when electrical light can keep you awake, allows full expression of pineal melatonin and maximize your chances of falling and staying asleep.Blue-Blocking Eyeglasses
Worn before sleep when pineal melatonin is on the rise, these eyeglasses allow full expression of the physiological sleep onset signal while maintaining clear visibility in normal room and screen light throughout the evening.Bright Light Exposure Risks
Light energy can interact with and damage skin and eye tissues, especially when using one of many photosensitizing drugs. Melatonin supplements may photosensitize light receptors in the retina when taken during daylight hours or under bright indoor illumination, a potential risk.Ask Our Experts
CET visitors have asked us questions about melatonin, and our experts have answered. Search this unique website feature.Basic research literature
Delve into the scholarly literature with selected journal articles and book chapters written for lab researchers and clinicians.