Time intervals for trading session
===

I'm having trouble figuring out which tradings session any particular time is in.

There are four possible sessions, show in this picture taken from ForexFactory.com

![enter image description here][1]


  [1]: http://i.stack.imgur.com/VlK5O.png

I have this method that I need to check is currentTime is during the specified trading session.

    public bool IsTradingSession(TradingSession tradingSession, DateTime currentTime)
    {

        //Regular session is 5PM - next day 5PM, this is the session in the picture.
        //Irregular sessions also occur for example late open (3AM - same day 5PM)  or early close (5PM - next day 11AM)
        DateTime sessionStart = Exchange.CurrentSessionOpen;
        DateTime sessionEnd = Exchange.CurrentSessionClose;

        if(tradingSession == TradingSession.Sydney)
            return ....... ? true : false;
        if(tradingSession == TradingSession.Tokyo)
            return ....... ? true : false;        
        if(tradingSession == TradingSession.London)
            return ....... ? true : false;
        if (tradingSession == TradingSession.NewYork)
            return ....... ? true : false;

        return false;
    }

Use: 

        bool isSydneySession = IsTradingSession(TradingSession.Sydney, CurrentTime);
        bool isTokyoSession = IsTradingSession(TradingSession.Tokyo, CurrentTime);
        bool isLondonSession = IsTradingSession(TradingSession.London, CurrentTime);
        bool isNewYorkSession = IsTradingSession(TradingSession.NewYork, CurrentTime);


Thank you