The crack of a Christmas cracker sounds the start of merry making around the dining table for millions on Christmas day. But this year festivities face going off without a bang as traditional snaps ...

Endorphins are the brain's "happy chemicals" and are released both to reduce stress and pain and in response to pleasurable experiences, such as laughing with friends over a truly terrible Christmas ...

The key to a good Christmas cracker joke is not whether it is funny but whether it can elicit groans around a dinner table, experts say "How much did Santa's sleigh cost? Nothing, it was on the house.