I signed a one year lease with my sister 3 months ago and now the tenants upstairs are making our lives beyond miserable. There is constant noise which prevents us from sleeping. Can we break our lease? We have already complained to the landlord . We also have begun to look for another apartment.

You will have to document the disturbance. This might mean calling the police in. What has the landlord done about your compaints?

If you can document, then send a notice to the landlord that, because of intolerable living conditions you are forced to find new lodgings and consider the lease null and void because of the conditions.