Equivalent Melanopic Lux (EML)
A measure of light’s impact on the melanopic photoreceptors, relevant for assessing circadian effects.
Circadian Stimulus (CS)
A metric quantifying the effectiveness of light in stimulating the circadian system, influencing alertness and sleep patterns.
Zeitgebers
External cues, like light and temperature, that help synchronize the body’s circadian rhythms to the environment.
Chronotype
Chronotype refers to the natural predisposition of an individual’s sleep-wake cycle and activity levels based on their circadian rhythms. It influences whether a person tends to feel more alert and active in the morning (morning chronotype) or in the evening (evening chronotype), or somewhere in between. These variations are essential in understanding personal differences in…
Sleep Hygiene
Practices that promote regular, restful sleep, including managing light exposure.
Melatonin
A hormone produced by the pineal gland in response to darkness. It regulates sleep-wake cycles by promoting drowsiness in the evening. Exposure to blue light (440-495nm) suppresses melatonin production, delaying sleep onset.
Suprachiasmatic Nucleus (SCN)
The suprachiasmatic nucleus (SCN) is a tiny region located in the hypothalamus of the brain, precisely above the optic chiasm – where the optic nerves intersect. It serves as the central circadian pacemaker, orchestrating the body’s internal clock and synchronizing various physiological processes to the 24-hour light-dark cycle. The SCN receives direct input from the…
intrinsically photosensitive Retinal Ganglion Cells (ipRGCs)
These specialized cells, known as intrinsically photosensitive Retinal Ganglion Cells (ipRGCs), are crucial for non-image-forming visual functions. They contain melanopsin, a photopigment that makes them sensitive to blue light, and play a key role in regulating circadian rhythms by relaying light information to the brain’s master clock, the suprachiasmatic nucleus (SCN).
Circadian Rhythm
The natural, internal process that regulates the sleep-wake cycle and repeats roughly every 24 hours.