I used to work night shift and tried a few different things. Maybe the super-premium blinds block more light, but IME the most effective solution is blackout curtains. You'll need to hang a curtain rod that's wider than the window and get curtains that are wide enough, ideally just a single curtain rather than 2 if your window is narrow enough.

Do you sleep during the day typically?

Mounted internal to the window frame, not external, works better for me. Internal can ride tighter to the window, so light can't go out the edges. With external frame mounting, you need much wider shades.

If the fabric itself isn't blocking light... You need better material. I have only ever had problem with light leakage in the edges, not in the fabric material.

I believe 'blackout thermal shades' is what to look for.

I have that. They have a magnet that keep the middle, where they connect light-tight.

Installation is key - they need to be oversized, covering the entire window AND the trim, and they need to be carefully installed so that they touch the trim.