British sleep researchers say night-shift work throws the body into chaos and could cause long-term damage.
Shift work has already been linked to higher rates of type 2 diabetes, heart attacks and cancer.
Now the Sleep Research Centre in southern England has concluded it has profound effects on the body at the deepest molecular level, affecting everything from athletic ability to brain function, the BBC reports.
Researchers at the centre say the body has its own natural rhythm or body clock tuned to sleep at night and activity during the day.
They admit to being surprised at the scale, speed and severity of the damage caused by being awake at night.