Insomniac contains Iglesias' first collaboration with a rapper - Lil Wayne - on the song "Push," as well as a cover of indie rock band Ringside's "Tired of Being Sorry".

[3] Insomniac features "Miss You", which is dedicated to his girlfriend, former tennis star Anna Kournikova, as well as a track, "Push", which he performs with rapper Lil' Wayne—a departure from his usual material.

[3] Allmusic reviewer Stephen Thomas Erlewine gave the album 2.5 out of 5 stars, writing: "'Insomniac' is pushed to a younger audience.

"[1] Lauren Murphy from Entertainment.ie criticized the songs, writing: "Every track here is either a sombre, mumbled, slow-moving number that sounds dated and cumbersome, cheesy radio-friendly dirges that have been done a million times before and better or are just so amateur-sounding that they're embarrassing.

"[5] Jonathan Bernstein from Entertainment Weekly wrote "Insomniac sees Iglesias possessed by the vengeful spirit of Toad the Wet Sprocket ("Stay Here Tonight"), outshone by Lil Wayne on the plodding club banger Push, and, yes, upstaged by a sampled Ping-Pong ball on Do You Know?

"[4] Joey Guerra from Houston Chronicle also gave to the album a positive review, writing: "Insomniac's secret weapons, however, are its ballads, which cast Iglesias as – of course – a sensitive, soulful Spanish lover.