nattlysende

Nattlysende (Norwegian for glow-in-the-dark or luminescent at night) is a term used to describe anything that emits light in darkness. The concept covers natural luminescence produced by living organisms as well as human-made materials that glow after being exposed to light.

Bioluminescence refers to light generated by a chemical reaction within living cells. It occurs in various organisms, including some insects, marine species, and fungi, and often serves ecological purposes such as signaling, predation, or defense. Phosphorescence describes materials that store energy from light and re-emit it gradually after the light source is removed, creating a persistent afterglow. Common phosphorescent pigments include legacy zinc sulfide-based compounds and modern strontium aluminate-based formulations, the latter providing longer afterglow in many glow-in-the-dark products.

Applications and occurrences: in nature, nattlysende phenomena are observed in fireflies and certain jellyfish and fungi. In human use, nattlysende materials appear in safety signage, emergency markings, watches and dials, toys, and decorative items. Consumer products often use phosphorescent pigments to achieve glow-in-the-dark effects, while chemiluminescence can be used in specialized applications but is less common for ordinary consumer items.

Limitations: the brightness and the duration of the afterglow depend on the material and prior light exposure; luminescence typically fades over minutes to hours. Environmental considerations include the production, use, and disposal of phosphorescent pigments and related chemicals.

See also: luminescence, bioluminescence, phosphorescence, chemiluminescence.