Little Girl Sleepwear

little girl
A girl is any female human from birth through childhood and adolescence to attainment of adulthood. The term may also be used to mean a young woman.
"Little Girl" is a single by American country artist Reba McEntire. Released in 1990, it was the third single from the album Sweet Sixteen. The song reached #7 on the Billboard Hot Country Singles & Tracks chart.
female child: a youthful female person; "the baby was a girl"; "the girls were just learning to ride a tricycle"

sleepwear
Pajamas or other clothing suitable for wearing in bed
nightwear: garments designed to be worn in bed