No matter what religions the people on your team follow, the end of the year is an ideal time to celebrate everything you've accomplished together, and to show your work family that they matter to you. That usually means a holiday party. But if you really want people to relax and have some fun for a few hours, the best thing you can do is host the party anywhere but the office.
How your brain keeps you from enjoying yourself
Every day, you come into the office environment and do very specific tasks. Over time, your brain learns to associate the space with those jobs and all the emotions that come along with them. You also make additional associations based on other memories you make in the space. For example, you might associate soda with your best work buddy because you both laughed so hard it came out your noses once, or you might hate a particular conference room because that's where you had to make the decision to lay off a quarter of your staff.
Sometimes, we can use these environmental associations to our advantage. Experts know that recreating elements from our space can help us learn and remember, for instance. This is known as state-dependent or context-dependent learning. But when you're throwing a holiday party at the office, those associations can make people feel like the event is just one more requirement or obligation. Because their brains have been trained to take specific behavioral pathways, it's very difficult for them to deviate from the habit, relax and get out of professional mode.
The solution, of course, is simple
Just get out of the office! This doesn't have to mean blowing your budget on a rented space. It could mean reserving a room at a local restaurant, potlucking at a local skating rink, or checking out holiday crafts and foods at a street market. You even could host a winter Olympics in your yard, have a cookie bake-off or do a holiday scavenger hunt. As long as it's novel and you make an effort for necessary accommodations, people should feel pretty good.
If you absolutely can't get out of the office for some reason, don't just hand out Santa hats. Do everything you can to make the room feel different. Try to get furniture out of the way, hide work tools with decorations, play holiday music, change the lighting--transform the place so that your brain sees it in a new way.
As you make your party plans, don't forget to weave in other activities that communicate the spirit of the holidays. For example, your team could volunteer at a shelter or nursing home, or you could host a toy drive and wrap them together. Give more than one opportunity here so that there are multiple chances for people to participate when it's most convenient for them. Ask people of different backgrounds and cultures what traditions they have to get more ideas. These are great, inclusive ways for your team to learn about what's needed most in the community and to let others outside of the office have some fun, too.