You don't wear pajamas to the office, why would you wear them to work at home? If you don't believe that how you are dressed makes a difference in your performance, test it out. Stay and work all day in pj's and slippers and the next day get dressed as you would for the office or meeting with a client. If it's business casual that you normally wear, then dress that way. But, at the end of the day, ask yourself honestly, if you noticed a difference in your concentration, your work and your confidence.
Professor Francis T. McAndrew, who teaches at Knox College in Illinois and specializes in environmental psychology—and yes, isolation—to see if there was a connection between getting dressed for the day and your general mental state. “If you look at how you are dressed, that signals something about what you are prepared to do. If you are dressed professionally and you’re dressed up, in some ways that raises your own opinion of yourself, and you want your behavior and demeanor to match the clothes."