She developed into a very inventive comedienne, with an animated face of many comic expressions—especially in the Charley Chase short The Rat's Knuckles (Martha's a waitress, registering confusion when a customer pours an entire bottle of soda on his sandwich) and in the Max Davidson short Pass the Gravy (Martha, imitating a chicken, thinks she has laid an egg).

In 1927, Sleeper was one of 13 actresses selected as a WAMPAS Baby Star,[5] whom exhibitors thought had a promising future in feature films.

Frustrated by the types of roles she was being offered, Sleeper began playing in local stage productions, at one point drawing raves as Eliza Doolittle in a performance of Pygmalion in 1932.

"Martha Sleeper was the leading lady and made her debut at Elitch in the 1944 season in Frederick Lonsdale's Another Love Story.

Aware of the pie-throwing antics of the Sennett studio, Martha chose to settle for a part with the Hal Roach comedy shorts.

[8] In 1945, as a favor to her Hal Roach director Leo McCarey, Sleeper played the role of Patsy's mother in The Bells of St. Mary's.

[9] While In New York, she turned a hobby into a thriving business, finding herself at the forefront of a fashion craze for "gadget jewelry" in the late 1930s.

In 1969, married her third husband and left San Juan for Beaufort, South Carolina, where she spent her remaining years.

Sleeper died of a heart attack, aged 72, in Beaufort, South Carolina, where she had lived with her third husband, Col. Howard C. Stelling, who survived her.

An airline passenger list, flight CBA 611 from St. Maarten to Charlotte Amalie, VI, on 10 Sep 1962, gives a birthdate of 6-24-1910, in Illinois (ancestry.com).

A U.K. Incoming Passenger list (ancestry.com) for the RMS Queen Elizabeth, from New York to Southamptom, arriving 19 Aug 1958, gives a birthdate of 24.6.10.

The Social Security Death Index records the date of birth of a "Martha Stelling" (Sleeper's third husband's surname) who died in March 1983 in Beaufort County, South Carolina, as June 24, 1910.