sleepless vs alert

sleepless is not a noun while alert is a noun.

Word	Noun	Adjective	Verb	Adverb
sleepless	No	Yes	No	No
alert	Yes	Yes	Yes	No

sleepless (noun)	alert (noun)
	a warning serves to make you more alert to danger
	an automatic signal (usually a sound) warning of danger
	condition of heightened watchfulness or preparation for action

sleepless (adjective)	alert (adjective)
always watchful	engaged in or accustomed to close observation
experiencing or accompanied by sleeplessness	mentally perceptive and responsive
	quick and energetic

sleepless (verb)	alert (verb)
	warn or arouse to a sense of danger or call to a state of preparedness