As shoppers look forward to hunting down traditional Boxing Day bargains, retail workers are filled with apprehension and worry, according to the poll gauging emotional responses.
Only one in four say the post-Christmas sales put them in a good mood, the study found.
The research was conducted by Adoreboard, an analytics firm based at Queen's University, Belfast.
It surveyed 1,460 people working in customer service roles in the UK.
More than half of those who responded (52%) believed their mood and personal feelings impacted the customers they served.
Rude customers were the chief source of stress for shop staff, with 70% of respondents saying bad manners were most likely to put them in a foul mood.
Long queues and panic shoppers were the two other main causes of concern.
Chris Johnston, chief executive of Adoreboard, said: "The study shows that emotions not only play a role in the decisions that customers make but also how people treat customers.
"Understanding the emotions of both employees and customers is key to unlocking how businesses can help people improve how they treat customers to achieve better results."
The survey coincided with the launch of CX Academy, an initiative launched by Adoreboard to examine and explore how customer experience can help businesses become more competitive.
It is being backed by Queen's University's business forum - the Chief Executives Club - and is supported by business support organisation InterTradeIreland and Zappos, the online American shoe and fashion retailer owned by Amazon.
Dr Alex Genov, Zappos head of customer research, said understanding how employees feel was hugely important.
"Fundamentally, it's hard to have unhappy employees and happy customers," he said.
"So understanding the emotions that drive how customers feel is vital to building a loyal customer base.
"Culture is critical to providing the glue to connect these two elements."
Professor Paul Connolly, pro-vice-chancellor of research and enterprise at Queen's University, said the project was an excellent example of how collaboration between research and business community could work.
"Customer experiences is the new battleground for brands to compete," he said.
"Improving competitiveness will be determined by less what you sell, and more about how you make your customers feel.
"To achieve this, you have to start by understanding your customers and employees as people."