Our sleep pattern is affected by our race, ethnicity and country of origin, two new studies have found.
US-born Americans sleep for longer than the recommended seven to nine hours each night, while African-born Americans sleep for just six hours or less. The sleep times of Indian-born Americans best fit the recommended bracket, with this ethnic group spending six to eight hours in their double storage beds each night.
The study by the State University of New York (SUNY) utilised the responses of 400,000 people who completed the National Health Interview Surveys between 2004 and 2010.
A second study by sleep researchers from Northwestern University Feinberg School of Medicine in Chicago also found that white people reported longer sleep times that any other ethnic group. Black people slept for the fewest number of hours, and Asian people reported the highest levels of sleepiness during the day. The findings were based on the survey responses of 439 randomly chosen people of both sexes from Chicago.
The Northwestern study's lead investigator, Dr Mercedes Carnethon, PhD, said the results represent the sleep experiences of a sample of the population who are healthy, as they did not include the response of participants who suffered from underlying sleep disorders in their published figures.
Other adjustments to increase the validity of the results were also made. Dr Carnethon said: “These racial/ethnic differences in sleep persisted even following statistical adjustment for cardiovascular disease risk factors that we already know to be associated with poor sleep, such as body mass index, high blood pressure and diabetes."