Abstract : Sleep can be defined as a reversible behavioral state of perceptual disengagement from and unresponsiveness to the environment. It is a complex mix of physiological and behavioral process which is generally seen with postural recumbence and closed eyes but not always. Sleep quality can be defined as “an individual’s self-satisfaction with all aspects of the sleep experience.” It has the following attributes which are sleep efficiency, sleep disturbances, sleep latency, sleep duration, wake after sleep onset. Sleep quality have been linked to various non-communicable diseases like diabetes, hypertension and heart diseases. The level of quality of sleep differs from region to region around the world. There are various factors which can affect the level of quality of sleep like sociodemographic factors which include age, location, gender, occupational type and income. Lifestyle habits including screen time, caffeine, nicotine, alcohol, exercise and stress can also affect sleep quality. Environmental factors such as noise pollution, temperature, exposure to light can also affect sleep. Poor sleep quality can also cause high economic burden for countries, increased healthcare costs and reduced workplace efficiency. Health of public and development of the country needs to improve the sleep quality of the population. This paper will look into the latest research on sleep, sleep quality, factors affecting it and sleep hygiene.