"Health care expenditures are nearly 50% greater for workers who report high levels of stress." -Journal of Occupational and Environmental Medicine
The National Institute of Occupational Safety and Health (NIOSH) 
defines job stress "as the harmful physical and emotional responses that occur when the requirements of the job do not match the capabilities, resources, or needs of the worker. Job stress can lead to poor health and even injury." Forty percent of workers surveyed by Northwestern National Life reported their jobs as very stressful. Other surveys show similar results.
What constitutes a stressful job situation varies from worker to worker. One employee may be invigorated by a challenging situation while another may be injuriously stressed in the same situation. For Example, one worker may find constant noise to be very stressful while another will be stressed by a feeling of work isolation in a quiet environment. This indicates a need to correctly match workers with job tasks.
Stressed employees may experience concentration difficulties, anger, sleep disorders, headaches, or a wide variety of other health issues.
Statistical Assessment Services (STATS) attributes the most costly work absenteeism to stress related physical and emotional problems.
Lifestyle changes such as adopting healthy eating habits, exercising regularly, learning cognitive-behavioral techniques and relaxation techniques are suggested by the
University of Maryland Medical Center as viable low or no cost stress-reducers.
The above sited
NIOSH publication discusses job conditions that may lead to stress, warning signs of stress, and useful suggestions your business managers and employees can adopt to reduce workplace stress.
Additional job stress and solution links:
The American Institute of Stress (AIS) includes a "Workplace Stress" quiz created by the Marlin Company and The American Institute of Stress.
HELPGUIDE.org explains stress management and how to reduce, prevent, and cope with stress.