Which version do you quote? All literal word for word translations for verse 13 have this:
English Standard Version
But we do not want you to be uninformed, brothers, about those who are asleep, that you may not grieve as others do who have no hope.
Berean Literal Bible
But we do not want you to be ignorant, brothers, concerning those having fallen asleep, so that you should not be grieved, just as also the rest, those having no hope.
New American Standard Bible
But we do not want you to be uninformed, brethren, about those who are asleep, so that you will not grieve as do the rest who have no hope.
King James Bible
But I would not have you to be ignorant, brethren, concerning them which are asleep, that ye sorrow not, even as others which have no hope.
Young's Literal Translation
And I do not wish you to be ignorant, brethren, concerning those who have fallen asleep, that ye may not sorrow, as also the rest who have not hope,
None of the literal versions have "who sleep in death" in verse 13. Why is this important? The added sleep in death makes it sound like soul annihilation and not using "sleep" "asleep" as the euphemism Paul has for the intended purpose. That's what it is here, a euphemism for death of a believer.
STRONGS NT 2837: κοιμάω
κοιμάω, κοίμω: passive, present κοιμάομαι. κοιμωμαι; perfect κεκοίμημαι (cf. Winer's Grammar, 274 (257)); 1 aorist ἐκοιμήθην; 1 future κοιμηθήσομαι; (akin to κεῖμαι; Curtius, § 45); to cause to sleep, put to sleep (Homer, et al.); metaphorically, to still, calm, quiet, (Homer, Aeschylus, Plato); passive to sleep, fall asleep: properly, Matthew 28:13; Luke 22:45; John 11:12; Acts 12:6; the Sept. for שָׁכַב. metaphorically, and euphemistically equivalent to to die (cf. English to fall asleep): John 11:11; Acts 7:60; Acts 13:36; 1 Corinthians 7:39; 1 Corinthians 11:30; 1 Corinthians 15:6, 51 (cf. Winers Grammar, 555 (517); Buttmann, 121 (106) note); 2 Peter 3:4; οἱ κοιμώμενοι, κεκοιμημένοι, κοιμηθέντες, equivalent to the dead: Matthew 27:52; 1 Corinthians 15:20; 1 Thessalonians 4:13-15; with ἐν Χριστῷ added (see ἐν, I. 6 b., p. 211b), 1 Corinthians 15:18; in the same sense Isaiah 14:8; Isaiah 43:17; 1 Kings 11:43; 2 Macc. 12:45; Homer, Iliad 11, 241; Sophocles Electr. 509.
As used by the apostle Paul in verse 13 it means death and not soul sleep. Paul would be contradicting himself as in
2 Corinthians 5 where he says:
6Therefore, being always of good courage, and knowing that while we are at home in the body we are absent from the Lord— 7for we walk by faith, not by sight— 8we are of good courage, I say, and prefer rather to be absent from the body and to be at home with the Lord. 9Therefore we also have as our ambition, whether at home or absent, to be pleasing to Him. 10For we must all appear before the judgment seat of Christ, so that each one may be recompensed for his deeds in the body, according to what he has done, whether good or bad. (NASB)
Paul clearly states when one is at home in the body they are absent from the Lord. Then taking the corollary with saying we prefer to be absent from the body and to be at home with the Lord. Chrystal clear here.
And his statements above would also be axiomatic as "death" in most of Scriptures means the separation of the soul or immaterial inner man from the material outer man or body:
Death, Death-stroke (see also Die)
[ A-1,Noun,G2288, thanatos ]
death," is used in Scripture of:
(a) the separation of the soul (the spiritual part of man) from the body (the material part), the latter ceasing to function and turning to dust, e.g.,
John 11:13;
Hebrews 2:15;
Hebrews 5:7;
Hebrews 7:23. In
Hebrews 9:15, the AV, "by means of death" is inadequate; the RV, "a death having taken place" is in keeping with the subject. In
Revelation 13:3,
Revelation 13:12, the RV, "death-stroke" (AV, "deadly wound") is, lit., "the stroke of death:" (
Death, Death-stroke (see also Die) - Vine's Expository Dictionary of New Testament Words
I've seen these before from a Bullinger site. Perhaps you could provide the context of said verses? And also include the use of the word death or breath in context as well?