The prevalent practice is that one eats in the "sukkah" on the eighth day, but without reciting the blessing ("berakhah") for sitting in a "sukkah". However, one does not take the "lulav" and "etrog" (nor does one sleep in the "sukkah" according to most opinions) on the eighth day. If someone sees a neighbor on the street with a "lulav" and "etrog" on the eighth day, the rabbis reason, s/he might mistakenly assume that it is still the seventh day ("ḥol hamoed"), when the "lulav" and "etrog" are still needed. S/he might then violate prohibitions of the "yom tov" of the eighth day. For that reason, the rabbis ruled that one should not take the "lulav" and "etrog" on the eighth day, even outside the Land of Israel. They are therefore "muktzah"; that is, one may not even move them on a holiday where they are not needed. Sleeping in the "sukkah" brings a similar discussion. Additionally, most people would prefer to sleep indoors at this point in the year due to the weather, so sleeping in the "sukkah" may impinge on one's own joy during the festival. This is why the rabbis ruled that one does not sleep in the "sukkah" on Shemini Atzeret, even outside the Land of Israel. Other rabbis, such as the Vilna Gaon, ruled that one should sleep in the "sukkah" on Shemini Atzeret outside the Land of Israel.