阅读短文，选出填入空格最合适的一项： Poor sleep is not jus…

阅读短文，选出填入空格最合适的一项：

Poor sleep is not just a personal problem; it is also costly for employers. Tired workers make more errors, take more sick days and are more likely to be injured at work. According to one estimate, lack of sleep ___ the loss of millions of working days every year in large economies. Some firms have started offering sleep workshops to their staff in response.