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From Dusk Till Dawn: Customizing Light Therapy to Enhance Your Circadian Rhythm

Updated: Feb 9

woman sittin by the window getting sun

The complexities of our circadian rhythms, which dictate our sleep-wake patterns and other physiological processes, are profoundly influenced by light. For those grappling with sleep issues related to shift work, delayed sleep phase syndrome, or simply wanting to wake up earlier, light therapy offers a beacon of hope. But how should one harness this light, and what are the optimum intensity, duration, and timing?

Light Therapy: A Bright Solution

Light therapy is the strategic use of light to realign our biological clocks with our desired schedules. The intensity and duration of light exposure, as well as the timing of the therapy, are crucial factors for effectiveness. Whether you're a night-shift worker aiming to stay alert through the night or someone trying to combat insomnia, the application of light therapy can be tailored to meet your needs.

Intensity: How Bright Should You Go?

The intensity of light used in therapy is measured in lux, with studies suggesting that even moderate light levels (about 1,000-1,200 lux) can be effective [12]. Full daylight can range from 10,000 to 25,000 lux, while a well-lit office might only provide around 500 lux. For therapeutic purposes, a level of around 10,000 lux is commonly used to mimic natural sunlight.

Direct or Indirect Sunlight?

Direct sunlight is most effective in the morning, promptly signaling our brain to start the day and suppressing melatonin production to enhance alertness [14]. Indirect sunlight, while softer, maintains our connection to the natural day-night cycle, supporting overall well-being [15]. Incorporating exposure to both types of sunlight into daily routines can optimize circadian health, improving sleep quality and daytime energy.

Thinking of buying a light therapy lamp?

Duration: The Length of Exposure Matters

When it comes to duration, more might be better than brighter. Research indicates that a longer exposure to moderate-intensity light might be more effective than a short burst of high-intensity light [1][12]. Typically, sessions can last from 30 minutes to 2 hours, depending on the individual's responsiveness and the light's intensity. Longer exposure to less intense light can enhance compliance and comfort, making light therapy a convenient addition to daily routines [1].

Timing: Synchronizing with Your Internal Clock

The timing of light therapy is essential. Morning light exposure can help advance the sleep phase, making it easier to wake up earlier [8][13]. Evening light, on the other hand, can delay the sleep phase, beneficial for those needing to stay awake later, such as night-shift workers [5].

Customizing Your Light Therapy

  1. For Shift Work: Exposure to bright light during the night, coupled with darkness during the day, can facilitate adaptation to a nocturnal schedule [12].

  2. For Delayed Sleep Phase: Morning light therapy can help shift your sleep earlier, realigning you with a more conventional schedule [8].

  3. For Waking Up Earlier: Similarly, morning light therapy is effective for those aiming to start their day earlier than their circadian rhythm dictates [13].

A Final Glow of Insight

Light therapy stands as a compelling method to control and modulate our internal clocks. With the right intensity, duration, and timing, it can be a powerful ally against various circadian rhythm disorders. As always, it's recommended to consult with a healthcare provider to tailor light therapy to your specific needs and ensure it is used safely and effectively.



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  2. Chang, A., Santhi, N., St. Hilaire, M., Gronfier, C., Bradstreet, D. S., Duffy, J., ... Czeisler, C. (2012). Human responses to bright light of different durations. The Journal of Physiology, 590.

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  4. Lucas, R., Peirson, S., Berson, D., Brown, T., Cooper, H., Czeisler, C., ... Brainard, G. (2014). Measuring and using light in the melanopsin age. Trends in Neurosciences, 37, 1-9.

  5. Czeisler, C. A., Allan, J. S., Strogatz, S. H., Ronda, J. M., Sánchez, R., Ríos, C. D., ... Kronauer, R. E. (1986). Bright light resets the human circadian pacemaker independent of the timing of the sleep-wake cycle. Science, 233(4764), 667-671.

  6. Smith, M. R., Revell, V., & Eastman, C. I. (2009). Phase advancing the human circadian clock with blue-enriched polychromatic light. Sleep Medicine, 10(3), 287-294.

  7. Yekzamani, P., Ashtarinezhad, A., Aboulghasemi, J., Masruri, B., Arabian, M., & Alimohammadi, I. (2022). Investigating the effect of different light intensities in work environments on Circadian rhythm using animal model. Occupational Medicine.

  8. Figueiro, M., Plitnick, B., & Rea, M. (2014). Pulsing blue light through closed eyelids: effects on acute melatonin suppression and phase shifting of dim light melatonin onset. Nature and Science of Sleep, 6, 149-156.

  9. Ding, J. M., Chen, D., Weber, E. T., Faiman, L. E., Rea, M. A., & Gillette, M. U. (1994). Resetting the biological clock: mediation of nocturnal circadian shifts by glutamate and NO. Science, 266(5191), 1713-1717.

  10. Desan, P. H., Weinstein, A. J., Michalak, E. E., Tam, E. M., Meesters, Y., Ruiter, M. J., ... Boivin, D. B., & Lam, R. W. (2007). A controlled trial of the Litebook light-emitting diode (LED) light therapy device for treatment of Seasonal Affective Disorder (SAD). BMC Psychiatry, 7, 38.

  11. Usui, S., Okazaki, T., & Takahashi, Y. (1999). The lower entrainable limit of rat circadian rhythm to sinusoidal light intensity cycles: A preliminary study. Psychiatry and Clinical Neurosciences.

  12. Martin, S. K., & Eastman, C. I. (1998). Medium-intensity light produces circadian rhythm adaptation to simulated night-shift work. Sleep, 21(2), 154-165.

  13. Rüger, M., St Hilaire, M. A., Brainard, G. C., Khalsa, S., Kronauer, R. E., Czeisler, C. A., & Lockley, S. W. (2013). Human phase response curve to a single 6.5 h pulse of short‐wavelength light. The Journal of Physiology, 591. The Journal of Physiology

  14. Gooley, J. J., Chamberlain, K., Smith, K. A., et al. (2011). Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. The Journal of Clinical Endocrinology & Metabolism, 96(3), E463-E472.

  15. Vandewalle, G., Collignon, O., Hull, J. T., et al. (2013). Blue light stimulates cognitive brain activity in visually blind individuals. Journal of Cognitive Neuroscience, 25(12), 2072-2085.



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