May eventually be related to the present root with unusual semantic derivations from ‘dark, darkness’ (cf. Bulakh 2006a, 198f.). See also dóhúm ‘heat-haze, shimmer’, edhím ‘to sleep with one’s wife when children or guests are sleeping in the same room’ (JL 36).
One cannot exclude that Hbr. nidhām “astounded, confused” (HALOT 214) belongs to this root with a metaphoric shift of meaning (< “dark, gloomy”, сf. Russian мрачный). Admittedly, the context of the only passage where it is attested (Jr 14:9) rather suggests the meaning “helpless”.