Example:

It must have been the edge of a dream, he thought.

This character is alone at this point.

Would you italicize the thought? Put standrad quotes around it? Single quotes? Or leave it straight, like it is?

Would you handle it differently if there was another character and it was in the midst of a conversation?

Thanks for your input.

Setting short passages of thoughts in italics has been a functional tradition for centuries, but preferences have been moving away from that for decades in some circles. Italicized thoughts cause confusion with italics used for emphasis, which is also deprecated in some circles. Long soliloquy-like passages of thoughts set in standard manuscript format with underlining indicating italics can be very jarring to a weary screening reader's eyes.

Bracketing thoughts in quote marks sets some grammarians at odds. It's not dialogue, does setting thought off in quotes make it confusing?

Tagging a thought with he thought, or the like, isn't as deprecated yet as italics or quote bracketing, but it's getting there.

The emerging preferred method is to so totally immerse readers in a point of view character's thoughts that no special indication is needed to recognize a thought as a thought and who thinks it.

Then again, generally I keep the thoughts to a minimum---generally no logner than Farnsworth's thought above. Often as not, I don't even underline, preferring to save that for emphasizing a word or two, or indicating a title, or somesuch.

Then again again...thoughts tend to be on the disjointed side, long, stream-of-consciousness things, often sentenceless, that if written down straight, really take up a lot of space on the printed page. (I remember a chapter of Titus Groan, where the characters sit around a table and their thoughts are all written out. Interesting enough, I thought, but can I handle something like that myself?