Many teens from lower- and middle-income homes get too little sleep, potentially adding to the problems of some kids already at risk for health issues, new research finds.
The study of 250 high school students found they slept an average of six hours a night, far less than the recommended amount -- about nine hours.
Kids who skimp on sleep are more likely to report feeling hopeless, as well as smoke, drink alcohol and use marijuana, according to background information in the report, published online April 21 in Pediatrics.
"Many teenagers, especially blacks, do not get enough sleep, which may contribute to their risk for poor health," said lead researcher Karen Matthews, a professor of psychiatry at the University of Pittsburgh School of Medicine.
"Inadequate sleep can result in academic underachievement, health-damaging behaviors and negative mood," she said.
Matthews said sleep deprivation isn't confined to the poor. "Many kids who come from upper class families also do not get enough sleep, but our study focused on poorer children because of a lack of data available in those [upper class] students," she said.
The researchers wondered if the challenges of living in disadvantaged circumstances would affect sleep patterns. In their sample, 60 percent of the kids lived in single-family homes. Overall, the kids were heavier than national average, the researchers said.
Matthews isn't sure why these teens aren't sleeping enough. "However, factors that determine bedtime play a key role for sleep duration because of mandatory school start times," she said.
"Bedtimes can be quite late if students are using electronic devices late into the evening, and bright light exposure [from these devices] can keep them up," she said.
Late-night studying was not a factor in this sample, Matthews said.
Dr. Metee Comkornruecha, an adolescent medicine specialist at Miami Children's Hospital, said the study shows "what a lot of us are thinking -- that adolescents aren't getting enough sleep."
Kids are prone to a lot of distractions, he said. "Cellphones are used not only for texting but to look on the Internet and for various types of social media. That frequent stimulation can keep these kids up."
Comkornruecha recommended removing electronic distractions from the bedroom. "Take the phones, computer and TVs away from the bedroom. If they're there, kids are going to use them. But if the bedroom is a safe haven for sleeping, then that's what it is going to be used for," he said.
Among the students whose sleep patterns were monitored, 57 percent were black and 54 percent were girls. All came from low- to middle-income families.
Matthews said besides looking at kids from poorer families, they wanted to look at any differences by race because two studies of middle-aged adults suggested that blacks had worse sleep than whites. "Thus, we conducted our study at an integrated high school that had black and white students of similar economic backgrounds," Matthews added.
The researchers had the students complete questionnaires and keep a diary of the length and quality of their sleep. At night, the teens were hooked up to an electronic device that monitored their sleep.
On school nights, the teens slept about six hours, and on the weekend, about seven hours. Matthews' team found that blacks and males slept less than other kids, and their sleep was more fragmented. Girls reported poorer quality of sleep and said they were often tired during the day.
Previously researchers have reported that insufficient sleep is linked to higher blood pressure and insulin resistance, a risk factor for diabetes.