[Mashimo]

Or as an alternative I use blackout curtains.

Once I also had automatic blackout blinds, they would slowly roll up before my my alarm rings. All controlled by home assistant, which can read the phono alarm time. Waking up slowly by light is nice :)

[Cthulhu_]

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.

[camillomiller]

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.

[khafra]

What about your rouladen? Articulated steel blinds block quite a lot of light, don't they?

[corgihamlet]

You mean "Rollläden", Rouladen are the rolled meat things.

[khafra]

Are you sure they're not the same thing? I'm quite certain I've heard people talk about "beef curtains."