Although the Health and Safety Executive does not consider that night work in itself poses a risk to workers' health or safety, night work can lead to health problems for employees with particular medical conditions. These include diabetes, heart or circulatory disorders, stomach or intestinal disorders, conditions that cause difficulties sleeping, chronic chest disorders, and medical conditions that require medication to a strict timetable. In order to meet their general health and safety duties, employers may need to consider transferring workers off night work if they have or develop any of these conditions.
The law also specifically acknowledges the particular nature of night work in two ways. First, night workers who are pregnant, breastfeeding or who have recently given birth may be entitled to be moved to day work, or to be suspended from work on full pay if no day work is available, if they have a certificate from their doctor or midwife stating that it is necessary for their health or safety that they should not work at night for a specified period (night workers ). Secondly, the Working Time Regulations 1998 impose limits on the length of night work (night work limits ) and require employers to carry out health assessments on night workers (health assessments ) and to transfer them to day work when necessary to protect their health, where possible (transfer to day work ). Young workers under 18 must not usually work at all at night (special hazards ).
For the purposes of the Regulations, a night worker is a worker who works at least three hours of his or her daily working time during night-time, as a normal course. This definitely covers workers who work at least three hours at night on a majority of their work days. It could also cover others. A court has held that a worker who worked at night for one-third of her working time was a night worker. The BERR guidance suggests that workers work at night 'as a normal course' if they do night work on a regular, as opposed to occasional, basis. A worker is also a night worker if he or she is likely to work at night for at least the proportion of his or her annual working time specified in a collective or workforce agreement (flexibility by agreement ).
Night-time is also defined in the Regulations. It must include the hours between midnight and 5 am. The other hours can be fixed by a relevant agreement (working time regulations), but if they are not, night-time is 11 pm to 6 am.
Under the Working Time Regulations 1998, employers must take 'all reasonable steps' to ensure that night workers' normal hours of work do not exceed an average of eight hours in each 24-hour period. As with the limits on weekly working time, the employer may need to take into account work that an employee does for another employer when assessing whether the employee is exceeding this limit. The night work limits can be modified or excluded entirely by a collective or workforce agreement, provided the workers concerned are given compensatory rest or, in exceptional cases where that is not possible, other protection for their health and safety.
A worker's average hours are calculated over a reference period of a rolling period of any 17 weeks in the course of the worker's employment, unless a relevant agreement specifies fixed successive periods of 17 weeks (such as, for example, each successive 17-week period beginning on 1 January 2007). For new recruits who have not yet worked for 17 weeks, the reference period is the period for which they have been employed.
In order to calculate a worker's average hours, it is first necessary to identify what his or her normal working hours are. This will involve looking at his or her working pattern over time including overtime.To work out the average:
- Take the number of days in the reference period.
- Subtract the number of hours the worker has spent on weekly rest entitlement under the Regulations (weekly rest periods ) divided by 24.
- Divide the number of normal working hours in the reference period by the resultant figure.
There are stricter limits for night workers involved in work that involves special hazards or heavy physical or mental strain. Employers must ensure that these workers do not work more than eight hours in any 24-hour period.
A worker's job definitely falls into this category if it is identified as involving special hazards or strain in a collective or workforce agreement that takes account of the specific effects and hazards of night work. A job also falls into this category if the employer has recognised that it involves a significant risk to health or safety in a risk assessment under the Management of Health and Safety at Work Regulations 1999. Work may be especially hazardous even if it has not been identified in one of these ways.
Workers under 18 are prohibited from working between 10 pm and 6 am. If their contract requires them to work beyond 10 pm, then the restricted period is 11 pm to 7 am. It is lawful to employ a young worker in this period only if he or she is needed to work immediately because of unusual and unforeseeable circumstances or exceptional events, the work is only temporary, and no adult is available to do it. The young worker must be given an equivalent period of compensatory rest within the following three weeks.
An employer must not assign a worker to night work unless the employer has first given the worker the opportunity to have a free health assessment. There is no need to offer an assessment if the worker had an assessment when assigned to night work on a previous occasion and the employer has no reason to believe that the original assessment is no longer valid.
Employers must also ensure that night workers have an opportunity to have their health reassessed at regular intervals, without cost to themselves. The frequently of this must depend on what is appropriate in a particular worker's case, in the light of the type of night work the worker does, its duration and the worker's age and state of health. Employers may need to obtain advice on this from a health care professional. The BERR guidance on the Regulations says that in many cases an annual assessment may be appropriate.
An employer has a similar duty to ensure that workers under 18 who are asked to work at any time between 10 pm and 6 am have the opportunity to have a free assessment of their health and capacities, before they are assigned and then at regular intervals. This should take into account whether the young workers' physique, maturity and experience makes them suitable for night work. There is no need to offer an assessment if the work that the young worker is assigned to do is of an exceptional nature.
The BERR guidance to the Regulations suggests that a health assessment can usually be limited to asking the worker to complete a questionnaire that asks specific questions about health that are relevant to the type of night work the worker will be doing. A medical examination will be necessary only where the questionnaire leaves the employer in some doubt about the worker's fitness to do night work. The guidance also suggests that employers should get help from a suitably qualified health professional when devising and assessing the questionnaire.
The Regulations prohibit the disclosure of an assessment to anyone other than the worker unless the worker has consented to the disclosure in writing, or the disclosure is simply a statement that the worker is fit to do night work. If the employee's own doctor produces a medical report for the assessment, the employee will have a right under the Access to Medical Reports Act 1988 to see the report before it is supplied and to refuse to allow it to be disclosed (written consent ).
If a doctor has advised an employer that a worker is suffering from health problems that the doctor considers to be connected with working at night, the Working Time Regulations require the employer to transfer the worker to suitable day work, where that is possible.
If a transfer to day work involves a change in a worker's contract terms, such as a reduction in pay, the employee's consent may be required. The issue of securing change in employees' contractual terms is dealt with elsewhere in this Guide ( Changes to contracts ).