Introduction to Light Therapy
Light therapy is a form of treatment where exposure to daylight or specific wavelengths of light is used for therapeutic purposes. It has a significant role in regulating the circadian rhythm, which is our body's natural clock, and in boosting alertness. Our internal clock, or circadian rhythm, synchronizes with the natural cycle of daylight and darkness, influencing sleep patterns, hormone release, and even body temperature [9]. Light therapy has also been found to increase alertness by suppressing melatonin, the hormone responsible for regulating sleep [1][2].
Who Can Benefit From Light Therapy?
Light therapy can be particularly helpful for those experiencing sleep phase disorders or adapting to shift work [4]. By exposing individuals to light at specific times, light therapy can effectively shift the circadian phase. Morning light exposure has been shown to advance the phase, ideal for those with delayed sleep cycles, while evening light exposure can delay the phase for those who fall asleep too early [10].
The Mechanism Behind Circadian Regulation
Light therapy regulates the circadian rhythm by providing signals to the brain's suprachiasmatic nucleus, which is responsible for maintaining the body's internal clock. Exposure to light, particularly blue light, can suppress the secretion of melatonin, a hormone that helps regulate the sleep-wake cycle, thus influencing circadian rhythms [5]. Bright light exposure has been shown to activate the adrenal gland, leading to increased corticosterone levels, which can enhance alertness [3].
Impact on Melatonin Production
Melatonin production is closely tied to light exposure. Light therapy, especially using blue-enriched light, can significantly suppress melatonin levels, thereby reducing sleepiness and increasing alertness [5]. This suppression varies depending on the light's intensity and wavelength, with shorter wavelengths (blue light) having a stronger effect [6].
Choosing Light Therapy Devices
When selecting a light therapy device to boost alertness, it's crucial to consider the intensity, wavelength, and duration of exposure. Devices providing an intensity of around 10,000 lux are effective for therapeutic use [7]. For reference, sunrise or sunset measures at around 400 lux, and full daylight can range from 10,000 to 25,000 lux [11][12]. For circadian rhythm sleep disorders, moderate-intensity light for a longer duration might be more effective than a shorter exposure to high-intensity light [8].
Thinking of buying a light therapy lamp?
Light Therapy Lamps on Amazon | What our founder Morgan uses
You even can pair your light therapy lamp with a smart plug to turn on 15-20 minutes before your designated wake up time to feel more alert!
What's the difference Human Light Therapy Lamps vs. Plant Lamps?
The primary difference between 10,000 lux light therapy lamps and plant lamps lies in their intended use and light spectrum. While 10,000 lux lamps mimic natural sunlight to influence human circadian rhythms, plant lamps are tailored to support plant growth and may not necessarily provide the full spectrum of light needed to impact human physiology [19].
Conclusion
Light therapy serves as a beacon of hope for those struggling with sleep and mood disorders. By understanding and utilizing the specifications of light therapy devices, individuals can profoundly impact their well-being, harnessing the power of light to stay alert and maintain a healthy circadian rhythm.
References
Chang, A., Santhi, N., St. Hilaire, M. S., Gronfier, C., Bradstreet, D. S., Duffy, J., ... Czeisler, C. (2012). Human responses to bright light of different durations. The Journal of Physiology, 590.
Chellappa, S., Steiner, R., Blattner, P., Oelhafen, P., Götz, T., & Cajochen, C. (2011). Non-Visual Effects of Light on Melatonin, Alertness and Cognitive Performance: Can Blue-Enriched Light Keep Us Alert? PLoS ONE, 6.
Ishida, A., Mutoh, T., Ueyama, T., Bando, H., Masubuchi, S., Nakahara, D., Tsujimoto, G., & Okamura, H. (2005). Light activates the adrenal gland: timing of gene expression and glucocorticoid release. Cell Metabolism, 2(5), 297-307.
Dewan, K., Benloucif, S., Reid, K., Wolfe, L., & Zee, P. (2011). Light-induced changes of the circadian clock of humans: increasing duration is more effective than increasing light intensity. Sleep, 34(5), 593-9.
Choi, K., Shin, C., Kim, T., et al. (2019). Awakening effects of blue-enriched morning light exposure on university students’ physiological and subjective responses. Scientific Reports, 9.
Cajochen, C., Münch, M., Kobialka, S., et al. (2005). High sensitivity of human melatonin, alertness, thermoregulation, and heart rate to short wavelength light. The Journal of clinical endocrinology and metabolism, 90(3), 1311-6.
Chang, A., Santhi, N., St. Hilaire, M. S., et al. (2012). Human responses to bright light of different durations. The Journal of Physiology, 590.
Dewan, K., Benloucif, S., Reid, K., et al. (2011). Light-induced changes of the circadian clock of humans: increasing duration is more effective than increasing light intensity. Sleep, 34(5), 593-9.
Cajochen, C., Münch, M., Kobialka, S., Kräuchi, K., Steiner, R., Oelhafen, P., ... Wirz-Justice, A. (2005). High sensitivity of human melatonin, alertness, thermoregulation, and heart rate to short wavelength light. The Journal of Clinical Endocrinology & Metabolism, 90(3), 1311-6.
Smith, K., Schoen, M., & Czeisler, C. (2004). Adaptation of human pineal melatonin suppression by recent photic history. The Journal of Clinical Endocrinology & Metabolism, 89(7), 3610-4.
McIntyre, I. M., Norman, T. R., Burrows, G. D., & Armstrong, S. M. (1989). Human Melatonin Suppression by Light is Intensity Dependent. Journal of Pineal Research.
Wirz-Justice, A., Schmid, A. C., Graw, P., Kräuchi, K., Kielholz, P., Pöldinger, W., Fisch, H., & Buddeberg, C. (1987). Dose relationships of morning bright white light in seasonal affective disorders (SAD). Experientia, 43, 574-576.