Health staff working poorly structured shift patterns can easily become dependent on caffeine to stay awake and pills to get to sleep, according to health workers union Unison.
Delegates at its health conference in Plymouth called for urgent action to tackle the stresses of alternating day and night shifts, because of the damage it can cause to physical and mental health.
Midwife Rachel Voller said thousands of NHS staff work shifts, and the number is rising.
“People are rightly worried about the long-term damage to their health caused by fatigue and difficulties with sleeping,” she said.
Last week, the Health & Safety Executive issued research showing that shift workers are more likely to suffer from heart disease, diabetes and other serious illnesses.