How does light therapy work in the body?
Light therapy – is a scientifically based method where specially dosed light affects the human body through the eyes and skin, regulating brain activity, hormone balance and biological clock. In Lithuania, this therapy is becoming increasingly relevant due to the long dark season, low natural sunlight in autumn and winter, and the increasing number of sleep and mood disorders.
Simply put, light therapy “reprograms” the body’s internal clock, helping it understand when it’s day and when it’s night. This is especially important for maintaining the balance of melatonin, the sleep hormone. This article explains in detail, how light through the retina and skin affects the brain, hormones, and overall well-being.
How does light therapy work on the eyes and retina?
Short answer: Light reaches the brain's biological clock through the eyes and regulates hormone production.
Key facts:
- Light enters the retina and activates special photoreceptors;
- Signals are transmitted to the suprachiasmatic nucleus (SCN) of the brain;
- The SCN regulates the release of melatonin and cortisol.
In addition to the visual cones and rods, the retina also contains intrinsically photosensitive ganglion cells (ipRGCs). They are particularly sensitive to blue light and directly signals the brain about the intensity of daylight, regardless of vision.
Scientific research suggests that it is these cells that are responsible for regulating circadian rhythms, rather than for visual perception.
How does light affect the brain's biological clock?
Short answer: Light synchronizes the body's internal time with the real circadian rhythm.
Key points:
- The SCN is considered the master “internal clock”;
- It responds to morning light;
- The sleep-wake cycle depends on it.
The suprachiasmatic nucleus (SCN), located in the hypothalamus, receives information from the retina and decides, Is it time for the body to be active or to restWhen a strong light signal is received in the morning, the SCN:
- Inhibits melatonin production;
- Stimulates the release of cortisol;
- Increases alertness and concentration.
For this reason light therapy is usually applied in the morning.
How does light therapy regulate melatonin balance?
Short answer: light helps melatonin be released at the right time of day.
Key facts:
- Melatonin is produced in the dark;
- Bright light inhibits its production in the morning;
- In the evening, melatonin rises again naturally.
Melatonin is the hormone that tells the body it's time to sleep. The problem arises when:
- There is a lack of bright daylight in winter;
- A lot of time is spent indoors;
- Screens are used in the evening.
Research confirms, that Morning light therapy helps restore normal melatonin rhythm, improves falling asleep and sleep quality.
How does light therapy affect other hormones?
Short answer: Light affects not only melatonin, but also mood and stress hormones.
Main hormones:
- Melatonin – sleep;
- Cortisol – energy and alertness;
- Serotonin – mood.
Light therapy increases serotonin activity in the brain, which is associated with improved mood and emotional stability. This is why this therapy is widely use seasonal affective disorder (SAD) in treatment.
Does light therapy work through the skin?
Short answer: yes, but by a different mechanism than through the eyes.
Important facts:
- Red and infrared light affect cells;
- Mitochondria are stimulated;
- Promotes tissue regeneration.
Through the skin, light affects cellular energy production (ATP), reduces inflammatory processes and stimulates blood circulation. This is especially relevant in dermatology and rehabilitation (source). However hormone and circadian rhythm regulation occurs almost exclusively through the eyes, not through the skin.
How does the use of light therapy in Lithuania differ from other countries?
In Lithuania, due to geographical features:
- During winter, daylight lasts only 7-8 hours;
- The number of sunny days is limited;
- SAD and sleep disorders are more common in the South than in the South.
Because of that Light therapy in Lithuania is becoming not an alternative, but a necessity for many people. In Lithuania, light therapy devices are available for purchase stokas.lt, which offers solutions that meet European standards.
Comparison of the benefits and effects of light therapy
| Area of influence | Mechanism of action | Result |
|---|---|---|
| Sleep | Melatonin regulation | Falling asleep faster |
| Mood | Serotonin activation | Lower risk of depression |
| Energy | Cortisol balance | Increased alertness |
| Skin | Cell regeneration | Better skin condition |
How to use light therapy safely?
- Use in the morning at the same time;
- Choose a 10,000 lux light source;
- Hold the lamp at a distance of 30-60 cm;
- Do not look directly at the light;
- In case of eye diseases, consult a specialist.
FAQ - Frequently Asked Questions
Conclusions
Light therapy affects the body through a complex but scientifically proven mechanism that begins in the retina and ends with hormonal regulation in the brain. It helps restore melatonin balance, improve sleep and mood. In Lithuania, where natural light is lacking for a large part of the year, this therapy is especially useful. When used properly, light therapy is safe, effective and is increasingly recommended by specialists.
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