Flight attendants aboard a trans-Atlantic B767-300ER reported feeling dizzy and light headed. The symptoms went away when the recycle machines were switched off and only fresh outside air was distributed. The dizziness returned when the recycle machines were re-engaged for a short period of time.

Narrative

Right after takeoff; on climbout; and also cruise; four of the five flight attendants working in the main cabin became dizzy; lightheaded; and nauseated. I was one of the four. I called the cockpit; the Captain said he had heard of this before. He said he was going to recycle the air; and to call him back. I did; and told him we all [still] felt the same. He then said he was going to circulate only fresh air. We all felt better right away. Right after meal and drink delivery; I felt dizzy again; as did the number 2 attendant. The number 2 then went to the cockpit. There the number 2 was told that they had just switched it back to recycle the cabin air; just like it was set after takeoff. So; the Captain stopped recycling the cabin air for the entire flight; and we all felt fine. One other odd thing. Normally you will have a line of passengers for the lavatories after the meal service or movie. Not one time did we ever have a line for the bathrooms; most passengers stayed in their seats for the entire flight. Very odd. I have never been on a flight like this before. It was almost as if they were all in a daze.