[4] "Enter Sandman" evolved from a guitar riff that Hammett wrote,[4] after being inspired by Soundgarden's 1989 album Louder Than Love.

[7][8] For the first time in Metallica's history, however, Ulrich and producer Bob Rock told Hetfield that they felt he could write better lyrics.

[12][13] Ulrich described "Enter Sandman" as a "one-riff song", in which all of its sections derive from the main riff credited to Kirk Hammett.

[18] After building again to a chorus, the song starts to fade out while the band plays the same riffs as the buildup intro in reverse order.

[20] According to Rock, Ulrich was the only band member who felt, even before recording, that "Enter Sandman" was the ideal song to be the first single.

[9] Ulrich has said that there was a "big argument"; however, after explaining his point of view to the rest of the band,[4] "Enter Sandman" eventually became the opening track and first single of the album.

1 on the Billboard 200 in the United States and nine other countries, and sold over 22 million copies worldwide,[21][23] allowing "Enter Sandman" to become, as Chris True describes it, "one of the most recognizable songs of all time in rock".

On September 30, 1991, it became Metallica's second single to achieve gold status in the United States, for shipping more than 500,000 copies.

1 after a CD single was re-issued whose profit is set to be donated for charity benefitting the German survivors of the 2021 European floods.

Chris True of AllMusic declared it "one of Metallica's best moments" and a "burst of stadium level metal that, once away from the buildup intro, never lets up".

[13] Steve Huey, in AllMusic's review of Metallica, described it as one of the album's best songs, with "crushing, stripped-down grooves".

[30] Sid Smith from the BBC called the song "psycho-dramatic" and noted that the "terse motifs served notice that things were changing" with Metallica's new album.

[31] Blender magazine's Tim Grierson says that the lyrics "juxtapose childhood bedtime rituals and nightmarish imagery" and praises the "thick bottom end and propulsive riff".

[42] According to Nielsen Music's year-end report for 2019, "Enter Sandman" was the eighth most-played song of the decade on mainstream rock radio with 126,000 plays.

[26] Andrew Blackie of PopMatters has said the video's "narrative suits the sludgy riffs and James Hetfield's twisted lullaby lyric".

Following its UK terrestrial broadcast of Live Earth, the BBC received 413 complaints and apologized to Metallica fans for cutting the band's set before "Enter Sandman".

The song was also used by NASA mission control CAPCOM B. Alvin Drew to wake up space shuttle astronauts aboard STS-123.

According to United States Psychological Operations, the intention was to "break a prisoner's resistance [... by] playing music that was culturally offensive to them".

The song was also sampled by British electronic duo Utah Saints and American rapper Chuck D on their track "Power to the Beats".

[56] The custom was started when the stadium installed a new scoreboard, and the team debated between using Guns N' Roses' "Welcome to the Jungle" and the Alan Parsons Project's "Sirius" before selecting "Enter Sandman".

[57] The song is now "the unofficial theme of the Virginia Tech athletic department," playing, for example, to celebrate the Hokies women basketball team's victory on March 27, 2023, that yielded their first trip to the Final Four.

[58] Since 2021, "Enter Sandman" has been used as entrance music for the Welsh Rugby Union and Premier League side Brentford FC during both sports teams walk-out onto the pitch.