Blackout curtains

[RipplePlease]

We live in a close and the man living opposite us has a security light which constantly switches on and off through the night and lights up our bedroom.
Would getting a blackout curtain eliminate this?

Some do and some are too thin or have pinprick hols which are annoying. I find it best with a blackout blind (but this can have gaps around the edges) and the blackout curtains. I can’t sleep with even a sliver of light in my bedroom. Doubling up fixes this.

We had this from the school across the road and they altered the angle when I asked, so that could be an option.

IME, light will get round the edges, even if the curtains themselves are really good, although it does help.