John Gill Commentary Genesis 19:35

"And they made their father drink wine that night also: and the younger arose, and lay with him; and he knew not when she lay down, nor when she arose." — Genesis 19:35 (ASV)

And they made their father drink wine that night also
Until he was drunk; which is an aggravation of his sin, that he should be overtaken a second time, and that so soon as the next night, when he ought to have been upon his guard, knowing how he had fallen into it the night before: and the younger arose and lay with him ;
arose from her own bed, and went to her father's, and lay down by him: and he perceived not when she lay down, nor when she arose ;
(See Gill on Genesis 19:33).