The aim of the paper is to determine the basic principles for long-term research on sleep quality depending on the quality of the indoor environment (IEQ). Sleep and rest are some of the basic natural needs. People spend about a third of their lives sleeping. Sufficient sleep helps us to think more clearly, to better and more consistently solve complex tasks that are important for everyday life. The quality of the indoor environment plays an important role in the well-being and health of building users. For quality sleep, it is also necessary to ensure appropriate factors of the internal environment as a whole. Insufficient quality of the internal environment, which has long manifested itself as the Sick Buildings Syndrome (SBS), has a significant negative impact on sleep and the possible development of sleep disorders. The importance of the quality of the indoor environment increases with the restriction of free residence in connection with the epidemiological situation of COVID-19.