Forex Correlating trade execution time with P/L outcomes

Has anybody correlated entry order time , on short term scalping type trades, with profitability (or the lack of it)There seems to be a much higher percentage of winners on those trades entered prior to 0630 Eastern standard/daylight time than those entered after said time,all other things being equal. Granted, after trading for 3 to 4 hours some fatigue may set in, or my attention to detail may fade somewhat, yet the results appear to be so consistent that I am wondering if anybody has experienced the same results.Your comments would be appreciated

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