This is a question I often get asked – how to make a bedroom completely dark for optimum sleeping conditions.  The first thing to understand is that while some window dressings can be described as ‘blackout’ in the case of blackout roller blinds for example,  it is only the fabric itself that is blackout, you will get slivers of light coming through at the sides of the blind which can be very bright!

Blackout roman blinds are better as they can be made to fit as closely as possible within the window recess.  For a truly blackout solution, pleated blackout blinds are a better option as they can go really tight up to the recesses. If it is just a temporary solution you’re after, then the paper pleated blinds eg, from companies like @Redishadeuk are a cost effective way of making the room dark behind another blind or curtains.   Finally, having blackout lined curtains work well too as although you might get some light appearing at the top (unless they go right up to the ceiling) this tends to be a diffused light which is less bright!