Hey! human being, two time steak challenge winner and armchair expert here!
It would actually be incorrect to refer to this as DayGlo - whether using the trademarked term or the colloquial 'genericization' - as it is plain old 'glow in the dark'.
The difference? The dayglo posters on your bedroom wall 'glow' in real time - best seen with a black light - while the glow in the dark stars that remain stuck to your ceiling from when you or perhaps an elder sibling was several years younger re-emit previously absorbed light.
LET ME EXPLAIN: Use of photoluminescent chemicals which fluoresce (give off previously absorbed light), as seen here, rather than photoluminescent chemicals which do not fluoresce (unless they're the more uncommon kind which are phosphorescent, to describe the property of fluorescent by means of phosphors) but rather re-emit 'reflect' light sourced from the UV spectrum into the visible light spectrum by effecting the wavelengths enough that they become within our visible light spectrum1 .
So, even when there is no source of visible light and we perceive the room as being completely dark - because our eyes cannot interpret ultraviolet light itself - there is still other light invisible to us so long as there is a source for it (such as an UltraViolet lamp) until it hits a surface with the property and the wavelength is transformed and emitted in a wavelength we can now see, giving the appearance of fluorescence whilst actually all happening in real time.
With that all in mind now, I reckon that the correct term for the image above would probably be fluorescent (which is by the way also commonly used incorrectly i.e 'Flouro' to refer to brightly coloured pigments that may not have the property to fluoresce at all)!
[1 For humans, not mantis shrimp. Mantis shrimp are an amazing predator for many reasons, one of which is that they can see in the ultra-violet light spectrum (amongst others) which makes you think "are the colourful markings of the peacock mantis shrimp there for predators who see in a specific narrow light band like us, or is what we see only the tip of the iceberg in terms of their colouration?" Mantis shrimp aren't just pretty creatures though. Their eyesight aids them in being a phenomenal marine assassin who can see you and are plotting your demise in every circumstance - unless you fry 'em up with butter, white wine and a little garlic, of course.]