5. Discussion and conclusion
major loss, insomnia, sleep deficiency, ’ behavior
EVENTS
Using a randomized controlled trial of a sleep improvement program in a firm’s workforce, this paper examined the extent to which improved sleep health increases work productivity. The results of the analysis revealed the following. First, participants in the sleep improvement program showed a statistically significant improvement in sleep health compared to the control group after accounting for a variety of work and lifestyle factors that may affect sleep. Second, the treatment group also exhibited a statistically significant improvement in work productivity, which was fully explained by the effect through sleep improvement. The total effect sizes for productivity improvement were similar whether the ANCOVA or 2SLS estimation methods that capture the effect through diligent participation or sleep improvement were used. Although it is possible for anyone to experience worsening sleep due to various changes and events in their work and personal lives, promoting sleep health through the use of information technology such as sensing devices may help improve sleep deficiency and restore productivity. However, the results of this paper also reveal that the effect is heterogeneous depending on individual characteristics such as age and willingness and perseverance to improve sleep health. When implementing proactive corporate health interventions, it is important to plan ahead, identifying groups of employees who might benefit most from interventions and incorporating additional nudges to support those who have difficulty changing their behavior.Currently, many developed countries are experiencing an aging population. Japan has the oldest population in the world, with the proportion of people aged 65 and over recorded at 28.7% of the total population in 2020, and this proportion is projected to rise to 35.3% by 2040. To cope with the aging of the population, the government is requiring companies to try to retain their employees until the age of 70 under the revision Act on Stabilization of Employment of Elderly Persons from April 2021. There is concern that as the number of people with sleep problems increases with age (see, for example, Léger et al. [As this paper has shown, poor sleep health leads to a decline in productivity, which is a major loss for the economy. The problem, however, is that when a person experiences chronically poor sleep, he or she may feel it is normal, and it becomes difficult for the person to recognize the decline in productivity. Additionally, even if the person is aware of productivity loss, companies may not be able to detect presenteeism. A person can see a doctor if he or she has extreme insomnia, but few people will see a doctor for a slight loss of productivity if it does not interfere with their daily lives. As a result, people tend to neglect their daily sleep, and even if they want to get a good night’s sleep, they are unlikely to actively gather information to improve their sleep health or examine related bad habits that negatively affect sleep. Companies should understand that the importance of sleep health is not easily recognized by individuals and may consider implementing proactive health management, such as providing sleep improvement measures or subsidizing the cost of sleep technology for employees.Finally, we discuss the limitations of our paper. First, we conducted an RCT on white-collar day workers as the main target group, and productivity improvements through sleep improvement were confirmed for those workers. However, it is not clear whether similar improvements can be expected for shift workers and blue-collar workers in various industries, such as construction, manufacturing, and transportation. It is necessary to verify the results by expanding the target occupations. Second, this paper targets workers who are interested in improving their sleep, and the sample size is not large (approximately 200 workers). It is necessary to examine the results of a larger sample including those who have sleep problems but are not interested in the sleep health measures or those who are strongly resistant to the interventions. Third, the effects of the RCT analyzed in this paper were based on data immediately after the program was implemented, and it is unclear how long the changes in the participants’ behavior to improve their sleep might last. Even if the advice given by the sleep app was temporarily beneficial, the improved behaviors may be reversed as soon as individuals stop using the app or sleep measurement device. Fourth, it is also necessary to examine whether productivity gains due to improved sleep are a temporary phenomenon or whether they persist. It will be important to monitor changes over time by conducting multiple follow-up surveys of RCT subjects. Fifth, the usage of actigraphy data recorded by the sleep device in the treatment group is another future challenge. We created the third sleep health score (