the single "Sunshine On My Back". The song is provided as a free download for renting or buying the band's documentary Mistaken for Strangers at its official website. The song comes from the Trouble Will Find Me recording sessions and features Sharon van Etten. The band headlined a handful of festivals during 2015, including Eaux Claires, a music festival held in Eau Claire, Wisconsin curated by Bon Iver frontman Justin Vernon and The National's Aaron Dessner. They also headlined Treasure Island Music Festival. In his review of the festival, Consequence of Sounds Zack Ruskin described the band's performance as "a masterclass in a band that has fully come into their own" and wrote that it "proved once again why they are one of the most exceptional and impressive rock bands of our time." On October 16, 2015, the band debuted a new song called "Roman Candle" (which would later be released as "Walk It Back" on Sleep Well Beast) at Troubadour in Los Angeles. In an interview published in November 2015, Berninger expressed the band's desire to play their new songs in a live setting before recording them: "Over the summer of 2016 we're going to do a lot of shows with the new stuff and then record the next National album." On March 2, 2016, it was announced that the band was to headline Latitude Festival in the United Kingdom. The same year they headlined such festivals as Byron Bay Bluesfest, Auckland City Limits, Field Trip, Down The Rabbit Hole, Super Bock Super Rock, Latitude Festival and Longitude Festival. They also played Free Press Summer Festival, Tinderbox, Pistoia Blues Festival, and the first annual Panorama Festival in New York City. In August 2016, Berninger indicated that the new album had electronic influences while they premiered the song "Prom Song 13th Century (Frankie & Johnny)" featuring St. Vincent. 2017–2021: Sleep Well Beast and I Am Easy to Find On May 11, 2017, the single "The System Only Dreams in Total Darkness" was released after two days of mysterious teasers. At the same time, a new album was announced, titled Sleep Well Beast, which was released September 8, 2017. The album's second single, "Guilty Party" was released on June 28, 2017. The band released "Carin at the Liquor Store", the third single from the album, on August 8, 2017. On August 29, 2017, they released the fourth single, "Day I Die".