As Rabbi Shimon ben Lakish said: The Holy One, Blessed be He, gives a person an additional soul on Shabbat eve, and at the conclusion of Shabbat removes it from him, as it is stated: “He ceased from work and was refreshed [vayinafash]” ...(Exodus 31:17).

An expanded "heart" for rest and joy, open to comfort, to eat and drink without the soul bothering her.