Californians really need a vacation.

Workers in California left 97 million paid days off unused in 2017, more than any other state, according to Visit California. About 58 percent of California workers left at least some of their hours unused, according to a news release from the state's tourism booster.

The numbers come from research commissioned by the U.S. Travel Association that surveys full-time employees who earn paid time off.

In all, California workers didn’t use about 30 percent of their 318 million days of earned time off. That beats the national average of 25.9 percent but falls behind five other states with more unused days by percentage, the release said.

California also accrued the most PTO days by volume, beating second-place Texas by nearly 90 million days. That helps to explain how California left 31 million more days untouched than any other state.

The 2016 data from the USTA placed five California cities in the 25 worst offenders for unused vacation time, the release said.

San Francisco-Oakland came in second in the country, with 64 percent of workers leaving vacation time unused. Sacramento came in 14th among the nation’s cities, with 55 percent of workers leaving behind PTO. Los Angeles, San Bernardino and San Diego all made the list as well.

Jan. 29 marks “National Plan For Vacation Day,” Visit California said in the release. The idea is to sit down and plan a trip or make plans for time off, so those accruing PTO can use it all. Previous USTA data show that people who plan trips are more likely to take them, said the release, so utilizing Plan For Vacation Day could help cement time off.

Work-related challenges often keep people from taking time off, according to a 2018 report from Project: Time Off, which studies vacation time in America (and partners with the USTA). According to the report, the biggest fears that kept workers from taking time off were looking replaceable, heavy workloads, lack of coverage at work and concerns about leaving pets behind.

In the same report, Project: Time Off said that workers who use most or all of their vacation time to travel reported “dramatically higher rates of happiness than those using little to none of their time for travel.”

These “mega-travelers,” as the report calls them, reported being 22 percent happier with their health and wellness, 13 percent happier in their personal relationships and 11 percent happier in their jobs than their non-traveling counterparts.