Excerpt from an article on ainonline.com:
​Wybbrandt, James. “Business Aviation Safety Summit 2016.” AIN Online. Web. 16 May 2016.

In years past many flight departments addressed fitness for duty, a prerequisite for safe operations, simply by asking pilots, “How are you feeling?” said Dr. Daniel Mollicone, president of Pulsar Informatics. Now it’s “a science with quantitative assessment,” allowing measurement of fatigue-induced impairment and the development of mitigation strategies. Pulsar provides fatigue-mitigation services to airlines and flight departments, and effective plans can be relatively simple, Mollicone said in discussing “Fitness for Duty: How Much Fatigue is Too Much?” In developing a solution for airlines, Pulsar found that it is usually only 3-5 percent of its flights created fatigue issues, which could be mitigated countermeasures such as providing crewmembers with hotel rooms for a 90-minute nap on a layover. “The risk reduction, for a total cost of a few hundred dollars, is dramatic,” he said.