The MSLT and MWT Should Not Be Used for the Assessment of Workplace Safety

Abstract

There is good evidence that the Multiple Sleep Latency Test (MSLT) and, to a lesser extent, the Maintenance of Wakefulness Test (MWT) are both reliable and valid measures of changes in sleep tendency in individuals exposed to sleep deprivation. The MSLT has been used extensively in both research and clinical settings for almost 30 years. It is only natural to wish to extend the use of these tests to other environments in which determination of alertness is essential. In research settings, group differences, often based upon large numbers of individuals, are identified at given levels of probability. However, in clinical practice, the focus is on the individual patient, and group information may be limited by individual variability. When one considers public safety, the focus shifts even more to include not only individuals, but also occupational groups, legislative bodies, employers, and unions. Even the most elegant test of alertness will be of no use in the face of work schedules that violate circadian adaptation or require chronic sleep deprivation or exempt themselves as too important or not subject to universal physiologic rules. A safe workplace requires the presence of specific items such as fire extinguishers and the absence of specific items such as fire arms and alcohol. Unfortunately, society has not accepted that sleepiness has no place in a safe workplace. Necessary evidence of such understanding would include consistent application of already published peer-reviewed empirical research to design work schedules and limit errors; provision of approved areas for naps (the fire extinguisher for mild sleep deficits); provision of sleepiness counseling as a part of employee orientation, continuing education, safety, and health services; and design of the workplace to maximize employee alertness. Acceptance of the importance of sleepiness evaluations will require public and professional education similar to that common for the negative impact of alcohol. Education programs stressing poor productivity and increased medical costs associated with sleepiness need to be directed toward government and corporate entities so that they recognize that improving alertness would pay tremendous monetary dividends in addition to improved health and would lessen the need for workplace tests of alertness. Remarkably, and regrettably, many sleep medicine practitioners have not followed their clinical wisdom into their own sleep schedule and the work-sleep schedule of their students and employees and can also benefit from education. Development times for recognition, treatment, and sanctions for alcohol use and smoking have shown that behavior change in society is a slow process that takes many years. Acceptance of sleepiness as an equally important medical and social problem will require the concentrated effort of our entire field for an extended period. Society now accepts the value of tests of breath alcohol in and out of the workplace. Significant education remains until there is a similar acceptance of the negative consequences of sleepiness. Such acceptance presages evaluations of alertness aimed at the patient (employee) rather than the disease (required working conditions). When given the mandate to evaluate alertness, our research must provide a reliable, valid test and appropriate norms for the group to be examined. Acceptance of the MSLT or MWT as a valid measure of alertness in normals and then in patients would be important first steps. Unfortunately, recent work suggests that our understanding of the relationship between sleep and alertness is still at a relatively rudimentary level. Additional empirical work is needed to properly place tests of alertness within sleep disorders medicine. Obviously, even more understanding will be required to extrapolate those links to the workplace.