Light is crucial for our physical existence and life, but it is equally essential for our mental well-being. We know this because throughout thousands of years, humanity has experimented and researched how the presence and absence of light affect our mood. One of the crucial tools that have been used in our quest for answers is the treatment known as light therapy.
The sun and its rays have always held a special significance for humanity. In many parts of the world, the sun has even been revered as a god to be worshipped and sacrificed to. It is therefore not surprising that we humans have always had a unique relationship with light and its rich potential.
A fascination spanning thousands of years
For thousands of years, scholars, researchers, and doctors have delved into the healing properties of light. As far back as 4,700 BC, the relationship between mood disorders and seasonal changes in light was mentioned for the first time in ancient China. It's clear that humans have always been fascinated by the connection between light and the human psyche, and it is based on this fascination that light emerged as a method of treatment.
From Hippocrates to the researchers of the 80s
The ancient Greeks were the first to discover the therapeutic effects of sunlight, which they called heliotherapy or sun therapy. Hippocrates, the father of medicine, described how sunlight could be used to treat mood disorders. For many years, sun therapy was the only form of light therapy available, until the invention of the electric bulb in the 19th and 20th centuries changed everything.
The advent of electric light marked the beginning of a revolutionary era in psychiatric light therapy, transforming sun therapy into light therapy. This new form of treatment, which involved UV-filtered light therapy and phototherapy with UV radiation, opened the door to more precise treatments tailored to patients' specific disorders and diagnoses. Light therapy became the norm for treating mental health conditions, while phototherapy excelled in dermatological treatments. In the 1970s and 80s, two scientific observations further deepened our understanding of the effects of light. Firstly, a study¹ demonstrated that altering the circadian rhythm in depressed patients could have a significant antidepressant effect. Secondly, another study² revealed that light inhibits the secretion of the circadian rhythm-regulating hormone melatonin. This meant that by exposing patients to the appropriate light, their circadian rhythm and sleep patterns could be stabilized, resulting in a natural antidepressant effect. It was during this time that researchers also discovered the direct link between the lack of light in the winter months and seasonal affective disorder (SAD)³. The research conducted in the 70s and 80s brought about a wealth of new knowledge about the relationship between light and mental well-being.
Back to the Beginning
Light is important to us, both when we are healthy and especially when we are sick - and here, treatment with the right light is an important tool for faster rehabilitation. In many ways, the function of light therapy is to bring us back to the starting point and ensure that our body's evolutionary need for light is met. Particularly in the winter months, light therapy functions to provide a boost of light, which is otherwise lacking in the northern hemisphere. In addition to therapy lamps and wake-up lights, circadian lighting has also become a larger part of modern light therapy. Automated circadian lighting is implemented in several psychiatric wards as part of psychiatric treatment. By providing patients with the right light at the right time, they can ensure a more stable circadian rhythm and better sleep without too many disruptions. A good circadian rhythm is essential because it acts as the conductor of the body. If the conductor is missing, the orchestra (all bodily processes) does not play in harmony, and this has both physical and psychological consequences. Getting the right light at the right times is therefore important both for preserving and treating the human psyche.
Sources:
- ¹Wehr TA, Wirz-Justice A, Goodwin FK, Duncan W, Gillin JC. Phase advance of the circadian sleep-wake cycle as an antidepressant. Science. 1979 Nov 9;206(4419):710-3.
- ²Lewy AJ, Wehr TA, Goodwin FK, Newsome DA, Markey SP. Light suppresses melatonin secretion in humans. Science. 1980 Dec 12;210(4475):1267-9.
- ³Rosenthal NE, Sack DA, Gillin JC, Lewy AJ, Goodwin FK, Davenport Y, Mueller PS, Newsome DA, Wehr TA. Seasonal affective disorder. A description of the syndrome and preliminary findings with light therapy. Arch Gen Psychiatry. 1984 Jan;41(1):72-80.
- Pierre Geoffroy (Paris Cité University, France): Light, mood and mental health. Seminar Series Current Topics in Sleep & Circadian Health.