P.S. Please don't take this as an endorsement of 4xmadeeasy. They are a B.S. site that happens to have a few useful slides.
P.S.S. There is a better slide that they have moved that I can't find right now. It shows the overlap of when the forex desks are open for each pair. When I find it again I will post it here.
The FOREX opens approximately 7.00 pm EST on Sunday evening – 10.00 pm UK time and closes Friday 4.00 pm EST
Every 24 hours there are 3 trading sessions.
Asia opens at 7.00 pm- 6.00 am EST
Europe opens at 2.00 am – 11.00 am EST
US opens 8.00 am – 5.00 pm EST 🙂