Heavy / blackout curtains are great for noise insulation / echoes / reverb / heat management, too. But there's often some leakage above and below, so a combination of blackout curtains, blinds, and / or outdoor blinds is likely the best option. But that's three separate investments and may not be possible if you rent.

Depending on your setup it might not be enough. I have those in the bedroom, but I can't install them on the rest of the flat (they're not the most beautiful). Leaving the bedroom door open for proper air quality leads inevitably to light coming in from other rooms. Yes it's that bright in Berlin at 4am in summer. Therefore I second the mask. There are a lot of option that are super comfortable and cheap on Amazon.