NBC/'The Tonight Show'

Watch Fun. Debut Their New Song, 'Harsh Lights'

You know what? I'm not sleeping tonight either!

Remember Fun.? You know, those guys who won two Grammys and ruled your world a couple years ago with a bunch of massive pop hits like "We Are Young"? Well, they're back and clearly the magic hasn't faded.

The group appeared on "The Tonight Show" on Wednesday night to debut their new single, "Harsh Lights," and, from the sound of it, they're jumping right back into the chart-smashing game. The majestic, "whoo-ooh-ooh"-filled mid-tempo anthem featured singer Nate Ruess' signature yearning vocals about bleary-eyed partiers looking for some meaning, hope and redemption in late nights under, yes, harsh lights. "There's such a fine line/but I'm not sleeping tonight," Ruess yelped in the pre-chorus. "We all got scars/I'm slipping into midnight under harsh lights/and nothing here is bringing me down."

And, of course, Bleachers frontman and Fun. guitarist Jack Antonoff was right by his side, ripping off a Queen-worthy guitar solo and big, crunchy chords.