The night session is very different to the day, often big spreads between the bid and ask and often very littlle volume, slippage if using stop orders is far more frequent and bigger than the day session
Be carefull if you trade it
Im a systems day trader and do very little overnight, although sometimes do have a position and stop in there, volume wise i only do 1 or 2 lots as it can be all over the place some nights if Europe and/or the US are volitile.