Then said Jesus, Father, forgive them; for they know not what they do. And they parted his raiment, and cast lots.

And the people stood beholding. And the rulers also with them derided him, saying, He saved others; let him save himself, if he be Christ, the chosen of God. And the soldiers also mocked him, coming to him, and offering him vinegar, And saying, If thou be the king of the Jews, save thyself.

And a superscription also was written over him in letters of Greek, and Latin, and Hebrew, THIS IS THE KING OF THE JEWS.

And one of the malefactors which were hanged railed on him, saying, If thou be Christ, save thyself and us. But the other answering rebuked him, saying, Dost not thou fear God, seeing thou art in the same condemnation? And we indeed justly; for we receive the due reward of our deeds: but this man hath done nothing amiss.

And he said unto Jesus, Lord, remember me when thou comest into thy kingdom. And Jesus said unto him, Verily I say unto thee, To day shalt thou be with me in paradise. Luke 23:34-43

Jesus didn’t even give this man time to take a nap!

We are confident, I say, and willing rather to be absent from the body, and to be present with the Lord. II Corinthians 5:8

The promise of heaven and being present with the Lord immediately, is only given to believers.

Remember your Creator before the silver cord is loosed, or the golden bowl is broken, or the pitcher shattered at the fountain, or the wheel broken at the well. Then the dust will return to the earth as it was, and the spirit will return to God who gave it. Ecclesiastes 12:6&7

It is not clear (to me) whether this verse is addressing only believers or mankind in general. What is clear, is that there is a separation of the body and spirit at death.

There was a certain rich man, which was clothed in purple and fine linen, and fared sumptuously every day: And there was a certain beggar named Lazarus, which was laid at his gate, full of sores, and desiring to be fed with the crumbs which fell from the rich man’s table: moreover the dogs came and licked his sores.

And it came to pass, that the beggar died, and was carried by the angels into Abraham’s bosom (paradise/heaven): the rich man also died, and was buried; And in hell he lift up his eyes, being in torments, and seeth Abraham afar off, and Lazarus in his bosom.

And he cried and said, Father Abraham, have mercy on me, and send Lazarus, that he may dip the tip of his finger in water, and cool my tongue; for I am tormented in this flame. Luke 16:19-24

It is also clear from this account of the rich man, that there is no intermediate state for the wicked either. The rich man died, was buried, and is in torment in the flames of hell.

When sleep is used as in the context of I Thessalonians 4:13-18, it is a metaphor for death.

…let the word of Christ dwell (take up its life) in you richly…