The aim of this research is to Know the the relationship between fear of Missing out (FOMO) and both of sleep disorders and social media sites addiction use, and also knowing the differences between Males and females in fear of missing out (FOMO), sleep disorders and social media sites addiction use, The sample of the research consisted of three hundred and five students, (124)male and (181) female from the second year students of the faculties of Education and Agriculture at Benha university, with average age = (19.2) year, and ST = (1.4) the two researchers uses fear of missing out (FOMO)Scale, sleep disorders scale and social media sites addiction use prepared by the two researchers, the results show that there are a positive statistically significant correlation between fear of missing out (FOMO)and sleep disorders, and also there are appositive statistically significant correlation between fear of missing out (FOMO)and social media sites addiction use, and there are differences between males and females in fear of missing out (FOMO) social media sites addiction use, and in sleep disorders such as insomnia, nightmares and disruption of wakefulness and sleep towards females, and there are no statistically significant differences between males and females in sleep companions, and also sleep disorders can be predicted by fear of missing out(FOMO), and also social media sites addiction use can be predicted by fear of missing out(FOMO).