Vodka, 7-Up and aspirin might sound to some like a hangover remedy, but believe it or not they are used by lot of people to keep their Christmas trees fresh.

But do they really work?

No, according to Chal Landgren, a Christmas tree specialist at Oregon State University. He said one of his research colleagues at Washington State University actually conducted an experiment putting Christmas trees in water mixed with things like vodka, 7-Up, aspirin or sugar.

He found none of those things helped.

"Just plain old water is all you need, and the only trick is to make sure you keep the water in the stand and don't put it near a heat source like a wood stove or right above the heater vent," said Landgren.

Landgren said there are some things you can do to keep your Christmas tree fresh. For starters, when you get it home, put it in water right away.

If you're leaving it outside for a bit, go ahead and fill a bucket with water and set the tree in there.

If it's been more than 24 hours since the tree was cut, or if you bought it from a lot, cut the end of the base off. About a quarter inch will do. The fresh cut will allow the water to more easily make it up into the tree.

Also, you might want to reconsider that tree-stand you have. Landgren said most don't hold nearly enough water. Your tree stand should hold a quart of water for every inch in tree trunk diameter.

But if your tree is already up and decorated in a too-small stand, don't worry. Just make sure it you water it every day.