Why is circadian disruption relevant?

We recently found reference to an 2007 meeting report from the National Institute of Environmental Health Sciences in the United States, where they discussed how best to conduct research on possible connections between lighting and health


The background notes to the meeting state:

Humans have evolved over millions of years and adapted to a solar day of approximately 12 hr of light and 12 hr of dark, latitude and season permitting. Our ability to artificially light the night began about 250,000 years ago when we discovered how to use fire. Candles were introduced about 5,000 years ago, and gas street lighting was possible beginning in the mid-1700s. However, only in the last 120 years has environmental illumination begun to change on a pervasive scale for the masses of people through the introduction of electric lighting.


One of the defining features of the built environment in the modern world is this artificial lighting. Electricity has made it possible to light the inside of large buildings and light the night for work, recreation, and security. The benefits of this lighting are obvious and enormous. It has become apparent, however, that although of obvious benefit, it may not be completely innocuous.


Light, including artificial light, can be potent in regulating human physiology and behavior and can therefore alter human physiology when inappropriately timed. One example of potential light-induced disruption is the effect of light on circadian organization, including the production of several hormone rhythms. Changes in light–dark exposure shift the timing of the circadian system such that internal rhythms can become desynchronized from both the external environment and internally with each other, impairing our ability to sleep and wake at the appropriate times and compromising metabolic processes. Light can also have direct acute effects on neuroendocrine systems, for example, in suppressing melatonin synthesis or elevating cortisol production that may have untoward long-term consequences.


The meeting concluded that maintenance of these circadian rhythms is important to health and well-being. And that the participants needed to focus on creating studies to advance our understanding of the impact of circadian disruption from lighting, and what then can be done to minimize or eliminate the adverse consequences for human health.



Related posts:

  1. Circadian disruption and breast cancer.
  2. Circadian rhythms and how to check yours
  3. Best of 2011 – Sleep
  4. Jet Lag and Light
  5. Why is Melatonin so important?


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