Health and Light

Light pollution is a threat to human health, the health of ecosystems, and esthetics.  There is a growing body of studies showing that

we are both overexposed to light at night, and underexposed to natural light during the day.

Light exposure affects our moods, hormones, fertility, and immune system. Excessive night light exposure is associated with increased breast cancers.

Earth Hour is March 24, 2018, 8:30-9:30PM local time. Turn off your lights.

The 12 Elixirs – chapter 21 – the fourth elixir: Sleep –

maintain a totally dark bedroom!

Get outdoors during the day!!!

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Increase in Artificial Night Sky Brightness in North America


Temporal organization of physiology is critical for human health. In the past, humans experienced predictable periods of daily light and dark driven by the solar day, which allowed for entrainment of intrinsic circadian rhythms to the environmental light–dark cycles. Since the adoption of electric light, however, pervasive exposure to nighttime lighting has blurred the boundaries of day and night, making it more difficult to synchronize biological processes. Many systems are under circadian control, including sleep–wake behavior, hormone secretion, cellular function and gene expression. Circadian disruption by nighttime light perturbs those processes and is associated with increasing incidence of certain cancers, metabolic dysfunction and mood disorders. This review focuses on the role of artificial light at night in mood regulation, including mechanisms through which aberrant light exposure affects the brain. Converging evidence suggests that circadian disruption alters the function of brain regions involved in emotion and mood regulation. This occurs through direct neural input from the clock or indirect effects, including altered neuroplasticity, neurotransmission and clock gene expression. Recently, the aberrant light exposure has been recognized for its health effects. This review summarizes the evidence linking aberrant light exposure to mood.

Transl Psychiatry. 2017 Jan; 7(1): e1017.
Published online 2017 Jan 31. doi:  10.1038/tp.2016.262
Clin Endocrinol (Oxf). 1998 Jan;48(1):73-9.

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