Yes, unless you have some programmed lights to help you wake up. Sleep normally ends as the sun starts shining. If you don't get that "signal", your body will have a harder time waking up, and be more confused about the right rhythm.

I have lived my whole adult life with black out shades and curtains. I grew up very rural and was used to a pitch black bedroom. As an adult I moved to the most densely populated state in the country, and immediately discovered black out shades.