Is it sufficient to recite the sleep invocations before lying down on the bed, or must they be recited while lying down on it?

The remembrances (adhkar) before sleep are to be recited after one has lain down, as this is what is mentioned in the noble Sunnah. In the Hadith of Ali (may Allah be pleased with him), it is stated: "When you both go to your beds, then glorify Allah thirty-four times..." And in the Hadith of Al-Bara' bin 'Azib (may Allah be pleased with him): "When you go to your bed... then say: 'O Allah, I have submitted my face to You.'" There is nothing in the Sunnah indicating that they should be recited before lying down, and the principle in acts of worship is to stop at what is prescribed. As for one who recites them before lying down on the bed, their action is permissible due to the general verses about remembrance, but they are not considered to have performed the Sunnah of the sleep remembrances.