The affinities outside Teut. are doubtful. Some refer the word to the pre-Teut. root *merk- to be dark; but the absence of consonant-ablaut, as well as the inappropriateness of the sense, seems to render this view less probable than the alternative hypothesis that the root is *mergh-, represented by the Lith. mirgu, to twinkle, margas parti-coloured. [OED 9:1086]Also relevant is the entry on ‘Morrow’, a word (now archaic) that comes via the ME ‘morwe’ or ‘moru’, both shortened forms of morwen, ‘the morn’.
Morning as the time of darkness (in the sense that it is when darkness dwindles, 'darkloss') doesn't seem so far fetched to me; but like the anonymous OED etymologist, I'm rather struck as the morning as twinkletime, howsoever twee that makes me.