There should be adult one piece pajamas with closed feet. Some people have poor circulation and need them to not get cold feet. For people trying to save money by turning the temperature extra low at night, it might even be a good idea to produce pajamas like that with the additional property that they're air tight everywhere except the zipper and the face and hand holes. Although there are some adult flannel pajamas with a matching top and bottom, there should exist a store, most probably Target, that will have some all year round ordering some more before it runs out. The more they order, the more factories will produce enabling them to keep ordering more before they run out.