One who sleeps little; (S, A, L, K;) as also ↓مُسَهَّدٌ: (A:) and some say سُهَدُ, like عُمَرُ; but this is [of a measure used] only in proper names: (Ham p. 39:) and an eye (عَيْنٌ) that sleeps little. (L.)
2.
[Hence,] (tropical:) Vigilant; cautious; applied to a man; as also ↓مُسَهَّدٌ. (A, TA.)