From: hubermanlab
Here is the edited article with backlinks included:

Phototherapy, the use of light to treat various health conditions, has been a burgeoning field within science and medicine. While many perceive phototherapy as a form of pseudoscience or “biohacking,” significant research and historical precedence substantiate its benefits. This article aims to elucidate the different types of phototherapy, their mechanisms, and applications, primarily based on the insights from the Huberman Lab Podcast.

Historical Context

Over a century ago, the potential of light therapy was recognized when Niels Finsen was awarded the Nobel Prize in 1903 for his work using phototherapy to treat lupus [00:01:37]. This laid the foundation for exploring light’s biological impacts, which continue to be refined and expanded upon today.

The Physics of Light

Electromagnetic Energy

Light is a form of electromagnetic energy that travels in waves. These waves can impact other objects and biological entities they encounter. Different wavelengths are associated with different colors of light, visible or invisible to the human eye [00:10:00].

Wavelength Penetration

A crucial aspect of light therapy is the depth of tissue penetration, which varies with the light wavelength. Shortwave light such as ultraviolet (UV) has limited tissue penetration, affecting primarily the skin. Conversely, longwave light like red and near-infrared can penetrate deeper into the tissues role_of_light_and_behavior_in_regulating_circadian_biology [00:16:02].

Types of Phototherapy

Ultraviolet B (UVB) Light Therapy

Mechanism and Applications

UVB therapy involves exposure to short wavelengths of light. It primarily impacts the skin’s surface and shallow tissue layers, influencing cellular functions such as melanocyte activity for pigmentation. UVB light has systemic effects, influencing hormone levels like testosterone and estrogen through pathways involving the skin hormonal_influences_on_hair_growth [01:08:42].

Health Benefits

Red and Near-Infrared Light Therapy

Mechanism and Applications

Red and near-infrared therapies use longer wavelengths to target tissues deep beneath the skin. These light forms interact with cell organelles like mitochondria to boost ATP production and reduce reactive oxygen species (ROS), critical for cellular energy and reducing oxidative stress mitochondrial_function_in_mental_health [01:45:00].

Health Benefits

Gamma Entrainment Using Sensory Stimulation (GENUS)

Mechanism and Applications

GENUS leverages specific light flicker patterns to induce brain activity rhythms (gamma oscillations), which are believed to promote cognitive function and potentially offset neurodegenerative diseases neurobiology_and_opthalmology [02:14:25].

Health Benefits

Considerations and Safety

While phototherapy holds remarkable potential, it necessitates appropriate application to avoid adverse effects such as skin damage or retinal injury. The intensity and duration of exposure, along with consideration of existing health conditions, are vital considerations for safe implementation of these therapies impact_of_sun_exposure_on_skin_health [02:02:06].

In summary, phototherapy presents a non-invasive, clinically beneficial approach to influencing biological pathways through light. As research progresses, the potential for integrating specific phototherapy techniques into health and wellness practices continues to expand, promising broader applications and improved health outcomes.