Another poll of more than 1,000 adults by the Principal Financial Group — a global investment company — found that 53 percent of people experience financial stress due to holiday spending, despite the fact more than half set budgets for their holiday spending.While these data suggest that the holiday blues are a real phenomenon, it's important to note that there are no systematic reviews or randomized controlled trials about mental health problems during the holiday season. The preliminary data indicate that this is a good topic for future research.