Light therapy to cure psychiatric disorders


Light therapy to cure psychiatric disorders

5 Oct, 2020

That light affects mood is not new, but that it can have a decisive positive impact in the treatment of patients with psychiatric disorders is extraordinary, especially considering the very solid scientific foundations on which this assumption is based.

Prof. Cristina Colombo, Professor of Psychiatry at the Vita-Salute San Raffaele University and Head of the San Raffaele Turro Center for Mood Disorders spoke to us about this.

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Importance of sleep

Before addressing the discourse on therapy we must make a premise on the importance of sleep, an incredibly intelligent mechanism. Sleep puts some functions of our body on standby mode, and allows us to save energy for our body.

Sleep also acts as a “cleaner” to the brain, as revealed by one of the latest studies on the subject: during deep sleep, a protein is activated which is responsible for opening certain channels in the brain, which eliminates harmful substances such as amyloid, which causes of Alzheimer’s dementia.

Good sleep quality can therefore help prevent dementia diseases as well.

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People suffering from psychiatric disorders usually show some typical alterations of biological parameters in association with symptoms and signs, among which we frequently find alterations in sleep rhythms.

In the course of a depressive episode, the subject typically falls asleep easily, then follows an early awakening characterized by strong anxiety, which persists in the early hours of the morning.

Bipolar patients, on the other hand, who go through euphoric and depressive phases, put in place a vicious circle in which the less they sleep the more they feel fit, to the point that they do not sleep at all and are very active.

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On the basis of these observations, sleep was considered a central moment, and therefore much studied. Today we know that sleep is regulated by a small area of ​​the brain where the biological clock resides, located inside the suprachiasmatic nucleus, a very small nucleus of cells that regulates the biological processes involved in the sleep/wake rhythm mechanisms.

The main external regulator of the biological clock, which actually activates it, is light: when this reaches the eye, it hits the retina, which sends signals to the biological clock, awakening it. The hormone responsible for this rhythm is melatonin, whose secretion is regulated by light.

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The benefits of light therapy

In a healthy person, following continuous switching on and off of the light, the melatonin peak changes: when the light is switched on, its secretion is inhibited, while on the contrary the dark stimulates its release.

Despite some discomfort, over time the unaffected subject still manages to maintain a fairly regular rhythm.

Through a scientific study conducted some time ago, however, it was shown that patients with depression or bipolar disorder have a lot of difficulty in regulating this rhythm: once the light is turned on, depressed patients are no longer able to adapt, while bipolar patients are no longer able to go back to sleep.

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The sleep disturbances associated with the particular sensitivity and influence of light have allowed us to formulate the hypothesis that mood pathology is a pathology of rhythms, and brightness could be closely related to the therapeutic response.

An empirical observation made it possible to demonstrate the irrefutable benefits of exposure to light: our department is completely randomly arranged so that there are rooms facing east and others facing west.Light_therapy_psychiatric_disorders_San_Raffaele_University (1)

During a morning in May we measured the difference in lux, the unit of measurement for illuminance, between the two areas: patients who were accidentally exposed to light have a faster hospitalization (they return home on average 2-3 days before). Repeating the procedure also in other clinics, for example in some centers in Berlin and Switzerland with which we collaborate, we obtain the same result: exposing the rooms to light leads patients to heal in less time, regardless of the drug therapy they are in.

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Florence Nightingale, the first nurse in history, had already arrived at the same conclusion, exposing her patients with surgical wounds to the Tuscan sun, which thus healed better and faster. While the biological reason may not have been clear at the time, today scientific studies have shown that light activates the enzymes responsible for repairing tissue damage, accelerating the healing process.

Hence the idea of ​​light therapy was born. For 30 minutes a day, upon awakening or at a fixed time determined by the doctor based on a test, patients are exposed to the light of a particular lamp. The light to which patients are exposed resembles that of a sunny day, devoid of ultraviolet and infrared frequencies, and has the purpose of resetting the biological rhythms affected by depression: it is therefore an antidepressant therapy in all respects, which it has no particular contraindications.

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The lamp in the “room of light” in San Raffaele Turro, which simulates daylight.


There are only a few simple rules that patients, guided by the hospital staff, have collected in a colorful poster hanging inside the “room of light”, a familiar, quiet and comfortable environment where therapy takes place.

  • During the exhibition it is important to keep your eyes open;

  • it is possible to read and leaf through a magazine (it is not necessary to look directly at the light);

  • after therapy it is also recommended to remain active throughout the day.
The important indications are not to keep the eyes closed (in order to obtain an effect, the light must be able to reach the retina and therefore the biological clock), not to go back to bed after the therapy and above all not to sleep (activities that would cancel the therapeutic effect).

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The instructions in the “room of light” in San Raffaele Turro


Today we use light therapy as an enhancement of drug therapies. In depressed patients the suicidal risk is very high during the first weeks during the therapies; light therapy greatly accelerates the effect of the drug, resulting in an improvement in mood and lowering the suicidal risk right away. Often, patients respond so well to light therapy that we can reduce the drug doses given to the patient.

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Sleep deprivation

Combined with light therapy, as an alternative or in addition to drugs, the Psychiatry Department has developed sleep deprivation, a non-drug therapy designed for depressed patients with bipolar disorder.

We subject patients to three phases of forced wakefulness, each of 36 hours, interspersed with three periods of nocturnal sleep during which the subject can sleep until spontaneous awakening. This sleep manipulation raises the serotonin level, bringing the mood back to a condition close to normal.

The nurses, specially trained for this therapy, keep patients awake with low-effort play activities, watching a film, making them refresh their faces every now and then, accompanying them on short walks in the open air. Depressive symptoms precipitate when we deprive of sleep, and incredible results are obtained from the first 'session'.

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First-choice therapies

What might initially seem like an obvious observation such as “using light to improve mood” has instead become a therapy that has attracted both the attention of major international scientific journals and the attention of many foreign university centers.

What we do in our department has a really solid scientific basis, so much so that the American guidelines suggest to use chronobiological techniques as the first choice for the treatment of psychiatric patients.

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The advantages of being admitted to our facility is that we try to limit the intake of drugs as much as possible, and we also carry out educational activities: for example, we teach the patient that sleeping well is important, because it prevents certain manifestations such as manic episodes.

This undoubtedly allows them to lead a better life: they are less hospitalized, take fewer drugs, do not lose their job, they have a better relationship with their family... these are therapies that can really have a decisive impact on people’s lives.

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UniSR Communication Team
UniSR Communication Team

Thanks to the contribution of the various team members, the UniSR Marketing and Communications Service deals with the multiple communication areas of the University: news scouting, creation of news, audio and video, event organization, website management and institutional social media, drafting and publication of newsletters, support for institutional relations. The Service interacts with all the main stakeholders (students, teachers, technical and administrative staff, research community, territory) in order to support and potential communication (internal and external) of the initiatives related to teaching, research and public engagement.

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