Person who lived above me in the last flat I lived in had a tendency to do this. Constant partying, door slamming, sex noises, and on one occasion, random schreeching at one AM. The fact that the person is still alive is a great testament to my self-control. Took several callouts to security and many grumpy emails to the landlord (who eventually threatened to fine them and withhold the deposit at the end of the tenancy) before it got stopped.
Other than that, earplugs are your friend, but it really shouldn't come to that. If you're really feeling petty, smack the roof with a broom or something at 6am.