Who is too old for shift work? Developing better criteria.

Demographic and social trends in industrialized countries are expected to lead to increasing numbers of older shift workers, raising concerns about possible health and safety risks. For older night workers, the International Labour Organization has recommended options for transferring to day work or early retirement, but few States have adopted these measures. For commercial air transport pilots, the International Civil Aviation Organization has implemented a series of regulatory measures that could manage the risks associated with aging, including a mandatory retirement age, regular medical assessments for fitness to fly, and limits on the duration of duty and rest. Each of these approaches has strengths and weaknesses. The mandatory retirement age is effectively arbitrary, has been controversial, and was recently increased from 60 to 65 yrs for one member of a two-person cockpit crew. Medical assessments offer a more individualized approach, but to improve safety, they must address aspects of health and physical or mental function that affect work performance and safety outcomes. The traditional focus has been on cardiovascular risk factors, although cardiac incapacitation is not a cause of accidents in a two-person cockpit aircraft. On the other hand, while pilot fatigue is an acknowledged cause of accidents, there is currently no requirement to consider issues associated with fatigue or sleep problems in fitness-to-fly medical assessments. Older long-haul pilots show greater sleep fragmentation than their younger colleagues and those in the general population. Sleep becomes more fragmented with increasing age, but the functional significance of this remains unclear. Among younger adults, experimental sleep fragmentation leads to increased sleepiness and degradation of performance and mood. Greater sleep loss is reported by older long-haul pilots, as well as other older shift workers, compared to younger people working similar duty patterns. Experimental sleep restriction causes a degradation of performance and mood that is cumulative and dose-dependent. In addition, a recent large-scale flight simulation study indicates that the duration of sleep obtained by individual pilots is an independent predictor of crew performance in a two-person cockpit. Based on these considerations, we propose that fatigue and sleep-related issues should become a standard part of fitness-for-work medical assessments, particularly for older shift workers. A multi-layered approach is proposed, with a routine structured sleep history leading to referral to specialist sleep services where appropriate. Criteria for specialist referral and medical retirement should be related to the workplace risk represented by an older worker. Additional research is needed to develop and validate sleep-related criteria for assessing fitness for work. For example, a better understanding of the effects of sleep fragmentation on the waking function of older workers might lead to a fragmentation threshold for fitness for work. The potential negative effects of unemployment and early retirement also need to be taken into account when considering the options for managing the occupational health and safety needs of older shift workers.