I used to have long drawn out dark periods but for the past few months they are much lighter in colour but very heavy and a shorter time, i'm in my 30's and not overweight/under weight etc.
Gone on the pill? Any other medication? PCOS? Exercising more? (personally I have found this makes a difference).
If you are worried, speak to your doctor they will be able to do tests/examinations to check if there's an issue or to reassure you that everything is ok.
I have been taking a friend swimming (she's ill so doing very little excercise) it's the only extra i'm doing, i never sit still for long normally, i also don't take any meds, but have cut out caffine. It's very difficult to get in at the doc's i may try the well women clinic. Thanks