Light and nature

Good illumination and a view of natural beauty aren’t just pleasant luxuries, but can make important practical differences in your life.

Light, especially daylight, has a strong effect on mood. There are at least fifteen controlled studies showing that bright light reduces symptoms of seasonal and nonseasonal depression by about 10-20% over placebo. This is about equal benefit to some antidepressant drugs, and sufficient that light therapy is a recognized medical treatment for depression. Bright light leads to self-reported better mood even in subjects without a diagnosis of depression, and also leads to better sleep and more agreeable social interactions.

Light and nature have positive effects on health. Some of the most compelling data comes from hospitals, which have long realized that their patients near windows do better than their more interior counterparts. In one study, surgical patients near windows recovered faster (7.9 vs. 8.7 days), received fewer negative comments from nurses (1.1 vs. 4 notes), and needed fewer strong painkillers (1 vs. 2.5 doses) than matched controls without a view. Other studies have compared recovery of physiological indicators of stress (for example, blood pressure) in subjects viewing natural or artificial scenes; the subjects with views of nature consistently have healthier stress reactions.”

17 children 7 to 12 years old professionally diagnosed with ADHD experienced each of three environments-a city park and two other well-kept urban settings-via individually guided 20-minute walks. Environments were experienced 1 week apart, with randomized assignment to treatment order. After each walk, concentration was measured using Digit Span Backwards…Children with ADHD concentrated better after the walk in the park than after the downtown walk (p=.0229) or the neighborhood walk (p=.0072). Effect sizes were substantial (d=.52 and .77, respectively) and comparable to those reported for recent formulations of methylphenidate.”

LED Light Considered Harmful


White LEDs are internally blue LEDs with a phosphor coating that shifts some of the energy from blue over to the rest of the spectrum - the reds, yellows, and greens. For most white LEDs, the blue light peaks around 450-480nm.

If you’ve ever wondered why white LED bulbs seem to fade gradually when you cut the power to them instead of just turning off instantly, this is why - the phosphor coating takes a bit of time to finish emitting.

The human eye has more than just the rods and cones. It has, discovered about 20 years ago (!), some additional cells that serve the rather specific purpose of detecting blue light. They’re known by the mouthful “Intrinsically-Photoreceptive Retinal Ganglion Cells”, or ipRGCs for short. These cells aren’t part of the visual system - they’re part of the circadian regulation system, and they work entirely independently of the rods and cones. Many people who are completely blind can still sense blue light (some report a sense of “bright” when in blue light that they don’t sense with other colors), and these receptors function as the “time synchronizer” for the human circadian rhythm.

The sensitivity curve for melatonin suppression - a peak around 477nm, with the 50% sensitivity level from 438-493nm. This peak also corresponds to the “clear blue sky” peak in normal daylight, amazingly enough.

Overall, we found that the use of portable light-emitting devices immediately before bedtime has biological effects that may perpetuate sleep deficiency and disrupt circadian rhythms, both of which can have adverse impacts on performance, health, and safety.


Related: Jevons Paradox. Increasing the efficiency of using a resource increases rather than reduces its use.

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01 Oct 2020 - importance: 6