Optometry Practice

Christl Huber M.D.
Optometry · Natural Medicine

Eyes control your inner clock

EYES Control Your Inner Clock

Release of important regulatory hormones such as serotonin, cortisol, adrenaline and melatonin occur within a normal 24-hour cycle called biorhythm or circadian rhythm. Light regulates this biorhythm. Our inner clock has a lot of extra work and stress keeping the body’s biorhythm with disruptions like jet lag, twice-yearly time changes, winter depression, and spring awakening.

Special photosensitive retinal cells in the eye direct light to parts of the brain that control biorhythm. Blue light activates these light cells. Natural sunlight is the most effective source of blue light. Brightness stimulates the light cells in the eye and hormone regulatory activity. In the darkness of night, the sleep hormone melatonin is poured out and we become tired and sleepy. If the correct light balance is disturbed, depression and other health problems can occur. Winter depression in the northern latitudes with limited sunlight is one of the best known disorders.

Artificial light sources have an influence on the biorhythm. Full-spectrum lamps get as close to natural sunlight as possible. Special lamps with a broad blue light content, called light showers, are useful in the morning. They activate positive light reaction in the body and act against winter depression.

Warm light fixtures with a high proportion of red light are suitable for evening use. High levels of blue light in energy saving lamps and LEDs used in computers, tablets, and smartphones suppress desired secretion of melatonin in the evening and make it difficult to fall asleep. Therefore you limit use electronic devices in the evening before sleeping and do not choose light sources with high blue light content.

The aging eye filters blue light. From the age of 45 (age of reading glasses), changes in the eye can occur that reduce the incidence of light on the retina. These include opacities and yellow discolorations of the eye lens (cataract) as well as cell deposits in the vitreous body. This filters the blue light and reduces the stimulation of the light cells. Studies have shown that opacities in the eye are often responsible for depression in the elderly.

A yellow discoloration of the eye lens on the other hand protects the retina from harmful UV radiation. For this reason, in star operations the clouded lens is replaced by a fine lens filter with fine yellow filter. The filter allows enough blue light for retinal stimulation but filters harmful UV light to prevent macular degeneration. Older people should regularly have their eyes examined for opacities.

With jet lag my recommendation is to change the clock immediately, wake up as usual in the morning, make everything bright, sleep as usual in the evening, if you cannot sleep at once, read a pleasant, non-exciting book or listen to soothing music in dim lighting. No electronic devices in the evening!

Researchers have found that movement in natural surroundings (not man made) is the most effective way to raise the mood. Ten minute walks daily have a positive effect. Neither computer simulations nor large nature paintings have this effect -- but a city park does.