Darkness is a necessity for optimal sleep. SleepOut’s curtains are hands down the best blackout curtains you can get. They are one-of-a-kind 100% blackout with ThermaGuard™ technology. Additionally, they do not off-gas any terrible toxins and are OEKO-Tex, Greenguard Gold, and SMETA-certified. You cannot find anything comparable elsewhere. They also have a portable option.