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Specific light can affect life's rhythms

Research has proven that specific light can affect and regulate the Circadian Rhythm and Melatonin secretion.

Light Effects

Built-in Body Clocks

Research over the last decade has identified that specific light can affect and regulate the Circadian Rhythm and, in turn, Melatonin secretion and its effect on all mammals.

Often referred to as the "body clock," the Circadian Rhythm is the 24-hour cycle that tells our bodies when to sleep, rise, and eat - regulating many physiological processes.

Types of Light

DairyLight delivers an optimized spectrum of light, at the right intensity to have a maximum effect on the Circadian Rhythm of the cow by regulating the secretion of Melatonin, also known as the sleep hormone.

Blue light within the short-wavelength blue light spectrum (465–485 nm) is the most effective at inhibiting Melatonin secretion, as Melanopsin production, its precursor is particularly sensitive to short-wavelength, blue light.

Normal white LED or fluorescent lights do not deliver blue light at the level of intensity required to have any real effect on Melatonin suppression.

Achieving Reaction Requires:

1. The right spectrum of light

2. The right intensity of light

3. The right circadian rhythm of light and dark

The system works by exposing the dairy cattle to a specific level and spectrum of light for 16 – 18 hours. When installed according to our bespoke design, this specific level and spectrum of light is delivered by our unique DairyLights. Melatonin production is suppressed during this time and cow activity and efficiency is optimised. This is followed by a period of darkness (or near darkness) for 6 – 8 hours, during which time melatonin production is stimulated and the cows rest and recover.

Light Spectrum Graphs

Key To Graphs:



Melatonin Suppression Curve




Red Light Function

Red light does not inhibit Melatonin secretion and hence the Circadian Rhythm. The controller automatically switches the DairyLight to red during the ‘off’ phase, and thus will allow sufficient observational light at night without interfering with Melantonin secretion. This is useful for calving as well as late arrival home.

The graph below demonstrates that red light does not affect the Circadian sensitivity and can be turned on at night for supervision and observation.

Red Light Spectrum Graph

Graph Key



Melatonin Suppression Curve

Circadian Sensitivity

Duration Of Light Exposure - The Natural Circadian Rhythm

In the northern hemisphere the daylight hours vary greatly between the summer months and the winter. For example, in December we have 8 hours of daylight and 16 hours of darkness. March to September there is equal day and night (Equinox). June has the longest day (summer solstice).

The Physiology Of Melatonin Control Using Specific Blue Light With Correct Lux And Duration

Light enters through the retina of the eye and suppresses the release of melatonin from the pineal gland, thus allowing the resumption of hormones to be released from the hypothalamus of the brain.

The Mechanism Of Melatonin

Melatonin is a pineal hormone produced during the hours of darkness, its pattern of secretion mimicking the light/dark patterns that occur during each 24 hour cycle. In breeding it acts as the daily decoder of seasonal changes in day length and regulates the circa-annual reproductive cycles of seasonally breeding mammals. The onset of the breeding season is triggered by increasing day length and concomitant reductions in Melatonin secretion.

The mechanism of Melatonin suppression has been well documented: light signals received by the retina are and processed primarily by the photopigment melanopsin, located within the intrinsically photosensitive retinal ganglion cells, travel along the retino-hypothalmic tract to the hypothalamic suprachiasmatic nucleus. The suprachiasmatic nucleus is connected to the pineal gland via the superior cervical ganglia and photic signals inhibit the release of the neurotransmitter norepinephrine, which therefore fails to stimulate the synthesis of Melatonin.

During long days the inhibitory action of Melatonin on the cow’s reproductive axis is lifted. GnRH (gonadotropin releasing hormone) is released from the hypothalamus and stimulates the production of hormones which in turn stimulates the anterior pituitary to release follicle stimulating hormone and luteinising hormone, which act in concert to promote the growth, development and ovulation of ovarian follicles.

Cows generally require 60-90 days of photo stimulation before the first breeding cycle of the season. To achieve a calving date closer to January 1st the cows' reproductive cycle must be tricked into resuming it earlier than is natural. This is done by artificial lighting.

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