The verb עָנָה (anah) comes in several forms including Qal infinitive, Niphal, Piel (as here), Pual Perfect, Hiphal, Hithpael. The form used in Judges 16:19 is Piel.
For completeness I have listed the meaning of this form of the verb below in an appendix as per BDB. Note that this word can mean "afflict or torment", but it can also mean to humble or weaken (see references below).
In this context, I note that whatever Delilah did (as per עָנָה) it was while Samson was still sleeping as it was only after he awoke that he realized that his hair had been cut off.
In fact, we are told what she did - she asked for hidden men to come out and cut of Samson's hair so that his strength would be gone; thus she would weaken and humble him. Benson observes:
She began to afflict him — To humble and bring him low, in which sense
the original word is often used. For, it seems, as soon as the razor
touched his head, his strength began to be diminished, which she
perceived by some means or other. He awoke and said, within himself, I
will go out as at other times — Samson probably did not find,
immediately after he was awake, that his hair was shaven, which made
him speak in this manner. He wist not that the Lord was departed —
That he was not present with him as he had formerly been; that he no
longer supplied him with that extraordinary and supernatural strength
with which he had before endowed him. And justly, indeed, did God
depart and withdraw his presents and gifts from a man who put it into
the power of a harlot to rob him of that which he knew had been
appointed the tenure whereby he was to hold them.
Many version correctly reflect this meaning here:
- NIV: and so began to subdue him
- NLT: In this way she began to bring him down
- BSB: In this way she began to subdue him
- CSB: In this way, she made him helpless
- HCSB: In this way, she made him helpless
- ISV: and so began to humiliate him
- NET: She made him vulnerable
- Darby: and she began to overpower him
APPENDIX: BDB meaning of עָנָה
Piel. Perfect3masculine singular עִנָּה Deuteronomy 22:24 5t.; 2
masculine singular עִנִּיתָ Psalm 88:8; 1singular עִנֵּיתִי Psalm
35:13, suffix וְעִנִּתִךְ consecutive Nahum 1:12, etc.; Imperfect
יְעַנֶּה Job 37:23, etc.; Imperative עַנּוּ Judges 19:24; Infinitive
absolute עַנֵּה Exodus 22:22; construct עַנּוֺת Isaiah 58:5 +, etc.;
Participle plural suffix מְעַנַּיִךְ Isaiah 60:14; Zephaniah 3:19; —
1 humble, mishandle, afflict: individual Genesis 16:6; Genesis 31:50
(J) Exodus 22:21; Exodus 22:22 (twice in verse) (E) Job 30:11; by
imprisonment and bonds Judges 16:5,6,19; Psalm 105:18; a nation by war
or in bondage Genesis 15:13 (J) Exodus 1:11,12; Numbers 24:24 (twice
in verse) (E) Deuteronomy 26:6; 1 Samuel 12:8 (inserting וַיְעַנּוּם
מִצְרַיִם, so ᵐ5 Dr Bu Kit HPS [compare Th We]), 2 Samuel 7:10; 2
Kings 17:20; Psalm 94:5; Isaiah 60:14; Zephaniah 3:19; dynasty of
David Psalm 89:23.
2 humble, a woman by cohabitation, Genesis 34:2 (J) Deuteronomy 21:14;
Deuteronomy 22:24,29; Judges 19:24; Judges 20:5; 2 Samuel
13:12,14,22,32; Ezekiel 22:10,11; Lamentations 5:11.
3 afflict as a discipline (God agent) Deuteronomy 8:2,3,16; 1 Kings
11:39; Psalm 88:8; Psalm 90:15; Psalm 119:75; Isaiah 64:11; Nahum 1:12
(twice in verse); Lamentations 3:33.
4 humble, weaken, object כֹּחַ Psalm 102:24; משׁפט Job 37:23 (compare
Talmud עִנָּה דִּין); נֶפֶשׁ oneself, by fasting Leviticus 16:29,31;
Leviticus 23:27,32; Numbers 29:7 (P) Psalm 35:13; Isaiah 58:3,5; by an
oath Numbers 30:14 (P).