CLC Human Centric Lighting & Wellness 2

Question 1

Which photoreceptor cell in the human eye is primarily responsible for circadian photoentrainment?

Accepted Answer

Intrinsically photosensitive retinal ganglion cells (ipRGCs)

Answer

ipRGCs contain melanopsin and project to the suprachiasmatic nucleus (SCN), making them the primary drivers of circadian photoentrainment.

Question 2

What is the approximate peak sensitivity wavelength of the melanopsin photopigment?

Accepted Answer

480 nm

Answer

Melanopsin has a peak spectral sensitivity at approximately 480 nm, in the blue-cyan range of the visible spectrum.

Question 3

A hospital patient room is being designed for post-surgical recovery. Which daytime CCT range best supports alertness and circadian health?

Accepted Answer

5000K–6500K

Answer

Higher CCTs (5000K–6500K) provide more blue-enriched light that suppresses melatonin and promotes daytime alertness, supporting circadian health.

Question 4

Which metric is used by the WELL Building Standard to quantify the circadian stimulus potential of a lighting environment?

Accepted Answer

Equivalent Melanopic Lux (EML)

Answer

The WELL Building Standard uses Equivalent Melanopic Lux (EML) to measure the non-visual, circadian-effective component of a lighting environment.

Question 5

Evening exposure to high melanopic illuminance primarily causes which physiological effect?

Accepted Answer

Phase delay of the circadian clock

Answer

Evening bright light exposure suppresses melatonin and shifts the circadian clock later, causing a phase delay.

(CLC) Certified Lighting Consultant Practice Test