Removing light as a cause for poor sleep is just a first step. In taking that first step, I would take overnight measurements in 27 places in the room and compare the graphs. Yes, it would take about a month to collect the data. At the same time, though, you could take sound and temperature measurements. Each morning the sleeper would log how good the sleep was. Diet and exercise are important to sleep and the sleeper should log these, too. Screen time is another important factor, as well as stress during the day. Drugs (including alcohol) should be noted. Some supplements, such as B6 at night, will affect sleep. Yes, this is a lot of work that takes a lot of motivation, patience and diligence. The alternative is have a professional sleep study done. Either way, anticipate a lifestyle change. be well