A heart attack is more likely to kill you if it happens on the weekend or at night, a new study shows.

It’s not that off-hours attacks are more deadly — it’s that hospital care may not be as timely, researchers reported Tuesday in the British Medical Journal online.

“We all know that hospitals have fewer staff and resources at night,” said the study’s lead author Dr. Atsushi Sorita, a senior fellow in preventive medicine at the Mayo Clinic Rochester.