OBJECTIVE: Nocturnal awakenings are one of the most prevalent sleep disturbances in the general population. However, little is know about how its severity affects co-morbidity with mental disorders and organic diseases. METHODS: A representative sample consisting of 8937 non-institutionalized individuals aged 18 or over living in Texas, New York and California states were interviewed by telephone. The interviews included sleeping habits, health, sleep and mental disorders. Nocturnal awakenings were evaluated according to their frequency per week and per night, their duration and the motive(s) for the awakenings. RESULTS: A total of 35.5% of the sample reported awakening at least 3 nights per week: 23% of reported awakening at least one time every night; 4.5% 5 or 6 nights per week and 7.9% 3 or 4 nights per week. Nocturnal awakenings increased with age only among people with nightly awakenings and were more frequent among women than men only among those awakening every night. More than 90% of subjects reported this problem lasted for more than 6 months. About 40% of subjects with nocturnal awakenings also reported other insomnia symptoms. Generally speaking, organic diseases and psychiatric disorders were more frequent among subjects waking up at least 3 nights per week regardless the frequency of nocturnal awakenings. However, nightly nocturnal awakenings were associated with more frequent organic diseases, obesity and psychiatric disorders. CONCLUSIONS: Nocturnal awakenings disrupt the sleep of about one third of the general population. Nocturnal awakenings are associated with a wide variety of organic diseases and psychiatric disorders that warrant appropriate treatment.