Lots of Vastu sources speak about energy / electric / magnetic forces / ions coming from the north. This is based on the polarities of our north and south pole.
Because our body also has magnetic forces / ions. The flow of "ions" from the north is said to have a big impact on our bodies.
Electrical magnetic forces in your house can be influenced by magnets, helping you to restore possible vastu deficit. Also be aware that electrical defices such as tv, mobile phones, fridge etc send out positive ions as well as certain weather conditions such a low presure fronts.
Read this website about North pole magnetism and how it can effect your health.
Other Sources:
Harmfull effects of Positive Ions - Pro Balance