when I

Ecclesiastes 8:7
Since no one knows what will happen, who can tell him what is to come?

Ecclesiastes 7:25
I directed my mind to understand, to explore, to search out wisdom and explanations, and to understand the stupidity of wickedness and the folly of madness.

there is that

Ecclesiastes 2:23
Indeed, all his days are filled with grief, and his task is sorrowful; even at night, his mind does not rest. This too is futile.

Ecclesiastes 4:8
There is a man all alone, without even a son or brother. And though there is no end to his labor, his eyes are still not content with his wealth: "For whom do I toil and bereave my soul of enjoyment?" This too is futile--a miserable task.

Ecclesiastes 5:12
The sleep of the worker is sweet, whether he eats little or much, but the abundance of the rich man permits him no sleep.

Genesis 31:40
As it was, the heat consumed me by day and the frost by night, and sleep fled from my eyes.

Psalm 127:2
In vain you rise early and stay up late, toiling for bread to eat--for He gives sleep to His beloved.