Sleeper Set is a fashion that was released in 1961.
"Ken® doll liked to get comfortable in his brown and white striped long-sleeved pajamas. Brown collar and pocket detailing added contrast to the set. But first, he needed a late night snack! A honey bun (wax) and glass of milk hit the spot. Don't forget to set the brass alarm clock! (The set is shown having short sleeves in the 1961 Mattel dealer catalog, but none have been reported on the market.)
All images and descriptions courtesy of Collector Books, publisher of "Barbie Fashion: Volume 1" and "Barbie Fashion: Volume 2" by Sarah Sink Eames
SKU #: 781"