마음속 영원함 [Credit] 1. Sleep Tight (Feat. Z.flat) Lyrics by Slevin, Z.flat Composed by Slevin, Z.flat, Boyrock Arranged by Boyrock All Instruments by Boyrock Except Guitar by 김호현 Recorded by Studio Ivy Mixed by EXMTL Mastered by 권남우 @ 821 Sound Mastering