Getting too little or too much sleep may worsen asthma in adults, a new study finds.

Researchers asked nearly 1,400 adults, 20 and older, with self-reported asthma about their sleep habits.

About one-quarter said they slept five hours or less a night (short sleepers), 66% slept six to eight hours a night (normal sleepers), and 8% slept nine or more hours a night (long sleepers).

Short sleepers were more likely to be younger and nonwhite, while long sleepers were more likely to be older, female and smokers, according to the study published recently in the Annals of Allergy, Asthma and Immunology.

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