Meanwhile, on the rise have been absences "related to obesity, treatment for skin cancer and herniated disc surgery."

Each of these factors has unique attributes that are keeping more folks at home.

Take the herniated disc syndrome. Cigna found that substantial advances have been made in treating the old bad back. But as new methods to ease the pain have emerged, more people are getting the surgery and so more are staying home to recover. The days of showing up to work in a back brace or downing Darvon are disappearing, but the lost days have actually increased over the last 20 years.

Obesity is another productivity theft. "Over the last 20 years, the number of obese Americans has doubled. At the same time, short-term disability claims related to obesity have increased by 3,300 percent," Cigna reports.

Interestingly, these claims are strictly related to obesity treatments, such as bariatric surgery. "This rise in the percentage of obesity claims does not reflect the impact of chronic conditions linked to obesity, such as diabetes and some musculoskeletal conditions," Cigna says.

Skin cancer offers a much more straightforward window into worker absenteeism. Whatever the causes — too much sunbathing, a perforated ozone layer, take your pick — the cases are way up. "Among different types of cancers affecting short-term disabilities, the biggest spike over 20 years was due to skin cancer – now five times more prevalent than in 1993. Skin cancer is the leading cause of cancer among 25-29 year olds as sun exposure and tanning represent significant risk increases."

The good news that Cigna found with respect to cancer is that regular screenings and new treatments have reduced its impact on worker absence over the last two decades.

"Overall, cancer screening and advances in medical treatment have reduced the number of cancer deaths and the duration of cancer-related disability claims. More survivors are now able to return to work, but employers should implement absence management strategies that integrate wellness programs, disease management programs and vocational rehabilitation services to meet the needs of cancer patients. Cigna's study showed that a combination of these programs helped 97 percent of survivors rejoin the workforce."

Depression stood out as perhaps the least understood cause of lost time at work, and the one with the potential to slowly drain productivity as people report to work battling the condition.

"Twenty years ago, depression was the third-leading cause of a short-term disability. Today, Cigna's data shows it as the fifth-leading cause. While related absences have been reduced slightly, depression still has a major impact on employers' bottom lines," the carrier said.

"More than one-fourth of Americans ages 18 and older suffer from a diagnosable mental disorder in a given year, and since 1993, the use of antidepressant medications increased from 37.3 percent to 74.5 percent," it said. "Advances in medication have helped, however this could also indicate an underlying problem of presenteeism.

"As more people fail to seek treatment, the longer and more deeply depression can impact an individual's health and an employer's workforce, which underscores the importance of an employee assistance program to help people with behavioral health needs to access care."