Blackout roller blinds can have side channels to prevent light entering at the sides.
Neat appearance as well as noise and heat insulation are added benefits.
This type of system is so robust that it can be fitted outside too.
Options include:
Fitting to sloped or curved windows
Fabric to lift from bottom of the window
Electric operation
RAL color side-channels
Twin blinds with translucent and blackout blinds in the same window
Blackout rollers with side-channels