Glow-in-the-dark. How does it work? In this video I show a bunch of phosphorescent samples and explain the difference between fluorescence and phosphorescence.

Link to my video about fluorescence: https://www.youtube.com/watch?v=blv1KxYLhc0

If you are interested in more you should search for chromium-activated zinc gallogermanate (Zn3Ga2Ge2O10 : 0.5%Cr3+). They glow invisble in near infrared but can glow for up to two weeks in the dark!
Hopefully the scientists will invent something similar that glow in the visible range for so long. I would definitely pay well for a phosphor that could glow on my watch for such a long time.

CREDITS
Music by:
Kevin MacLeod from www.incompetech.com
Tracks used:
0:00 - ISRC: USUAN1100420 - Long Note Two
4:00 - 4:19 ISRC: USUAN1100621 - Impact Andante
5:20 - 5:27 ISRC: USUAN1100196 - Inner Sanctum
Licensed under Creative Commons: By Attribution 3.0
http://creativecommons.org/licenses/by/3.0/

Outro music (5:39 - 6:26):
Track Name: Down (http://freesound.org/people/dingo1/sounds/174589/)
Composer: Marcus Dellicompagni
Website: www.RedAudioUK.com
Licensed under Creative Commons: By Attribution 3.0
http://creativecommons.org/licenses/by/3.0/

Sound effects:
www.freesound.org
* Toads and frogs are singing at night in the pond, in the center of the small village of Diafarabe, on the Niger river. (Africa, Mali)- felix.blume
* kc_animal_frog-lakeside-penticton-2013.wav - kayceemixer
* deep sea ambience - jhumbucker
**lucid drone.wav - decembered
**dawn chorus.wav - juskiddink

* Licensed under Creative Commons: CC0 1.0 Universal (CC0 1.0)
Public Domain Dedication
http://creativecommons.org/publicdomain/zero/1.0/

** Licensed under Creative Commons: By Attribution 3.0
http://creativecommons.org/licenses/by/3.0/