"When you finish work, there's still a mountain to climb before you actually get to Christmas Day. You're buying things, there's a lot of logistics.
"We're tired and when we're tired, that increases our emotional vulnerability to things going wrong. The next thing is financial stress. That's huge, we feel at this time of year that we're haemorrhaging money trying to keep everybody happy, so that puts a huge amount of pressure on people."
She says Christmas comes with expectations of togetherness and that can put pressure on people who might be alone or unhappy.
"I think most people understand there's an underbelly to Christmas that's not particularly tasteful, and that's the domestic violence statistics that go up, the drinking, the addiction problems. A lot of people are worrying and struggling at this time of year with mental health issues."
Nimmo says she's had clients that just avoid the day altogether to dodge the stress and pressure that comes with it. She says that, for many, Christmas is a day that reminds us of loss. For many it will be the first Christmas without a family member who may have passed away.
"And it goes on, it's not just the first Christmas, it's the second Christmas and then it sets up a negative view of the whole occasion which is quite understandable when you've been through that kind of thing.
"You can put on a bright face, but you can't force people to be jolly."
She says there are things you can do to make the day easier. For instance, structuring the day and planning the meal.
"But that doesn't stop people's personal feelings creeping in around the edges."
Nimmo says it can help to take some of the hype out of Christmas and remember it's just another day in the calendar.
"It doesn't have to be the best day you ever had, the most together, the most glorious, the best food. It can be just another day if that's what is going to work for you, and I think that's important."
There's also the problem with family members that get under each other's skin. Nimmo says we need to emotionally prepare ourselves for these encounters which are often unavoidable.
"If you can't move your placemat to the other end of the table, then you really do need to think about how to manage Uncle Stu, or a sister that they just don't get on with.
"In families we have old roles that we settle into and those are very hard to bust out of. We've got the spoiled older sister, or the bossy younger one, and we somehow revert to those people."
The other thing to be aware of is alcohol intake. Many families and people start drinking very early in the day which can lead to shenanigans later on in the afternoon or evening. Nimmo says we should monitor our own intake before anyone else.
"We know with couples we work with that their worst and most violent fights happen when there's alcohol or drugs in the mix. At all costs, that should be cut down or avoided - not to be a party pooper - but at least reduced."
