It is hard to imagine a more disparate couple than Yitzchak and Rivka, the quiet contemplative husband who would "meditate in the fields" (24:63), and the worldly, independent-thinking wife who “ran again to the well” (Breisheet 20:24). Yitzchak spent his entire life in the land of Israel, never traveling the world. He was, as our Sages describe him, "a pure offering", ready to sacrifice himself to G-d. He could see no evil in others, and thus could be easily fooled by both Eisav and Yaakov.
Yaakov Avinu was on the run. Forced to leave home after "stealing" the birthright from his brother, he was attempting to stay one step ahead of Eisav, who was busy planning for the day when he would "be able to kill my brother Jacob" (27:41). Understandably, Yaakov was fearful. It was at this point, our Sages teach us, that he instituted Maariv, the nightly prayer service, night being the symbol of fear and uncertainty.
Tired from being on the run, he lay down for some much-needed rest.