Before assigning an adult to night work, the employer must offer a free health assessment (regulation 7(1), WTR), unless the worker has previously had an assessment and there is no reason to think it can no longer be relied on. Free repeat assessments must be offered at regular intervals, such as annually. The assessment must be by a qualified health professional, but it can take the form of a questionnaire. If the employer is unsure of the worker’s suitability for night work after reviewing the questionnaire, the worker should be asked to undergo a medical examination.