It's the M in Sleep Disorder PLMD
This page is the CodyCross answer for the clue below from Extraordinary Creatures, Group 1598, Puzzle 1 (Leaf Tailed Gecko).
Question is: It's the M in Sleep Disorder PLMD
and the answer is: MOVEMENT
Word Meaning:
MOVEMENT — Physical motion between points in space.
Definitions from Wiktionary.