Shalom, I never heard of a source that says one should say Hamapil standing up, most people say Hamapil right before they got to sleep and that can be done sitting or lying down. According to most Poskim one can still talk a bit or eat or drink a bit if he/she really needs to and it’s ok BUT it is highly recommended not to speak, eat or drink after saying Hamapil. Both the Ari’Zal and the Ben Eish Chai say it is very important not to speak, eat or drink after saying Hamapil and that is what we go by. So to look a bit on your phone right before you fall asleep is fine, but one should not watch a whole movie after saying Hamapil. You can find sources about Shma and Hamapil in: – Shulchan Aruch – Orach Chaim 239/1 שולחן ערוך אורח חיים · רלט · א – Kitzur Shulchan Aruch – 71 קיצור שולחן ערוך · סימן עא – Tractate Brachot page 60/2 מסכת ברכות, דף ס’, עמוד ב Rabbi Alon Anava