Starting the party before it's supposed to begin can lead to over-indulgence of alcohol.

Researchers in Switzerland wanted to see the impact of frontloading alcohol -- that is, drinking before going out for the evening.

Using questionnaires -- researchers found young people who indulge in so-called "pre-drinking" often end up drinking twice as much as they might in a regular outing.

They were also more at risk for hangovers, drug use, blackouts, injury and unprotected sex.