Ecclesiastes 5:12:

The sleep of a laboring man is sweet, whether he eat little or much: but the abundance of the rich will not suffer him to sleep.

Notes on Ecclesiastes 5:12:

You would think that it would be the poor who would toss and turn all night because of their dire financial situations.  While that could happen, Solomon shows here that a rich person, who has much more to lose, could actually have it worse at night, at least if he is not trusting God to be his Provider.  Even today there are well-off people who are nervous at night wondering what their financial investments might be doing overnight.

See also:

Condition: Insomnia