I know this is vague but I have been plagued with bouts of sleepiness that come on suddenly. I do suffer from insomnia but this seems unrelated to whether I have had a good nights sleep or not. I don t drink caffeine after 5 pm, I ve cut out the excess sugar and other unhealthy eating habits. I have previously been tested for hypothroidism and diabetes with negative results. My iron levels have always looked good and taking vitamins does not improve the situation. This sleepiness also does not appear to be related to being overworked. Although it does seem periods of cold and or flu symptoms . As a teenager I was once diagnosed with mono and this sleepiness seems very similar to that condition which I understand a person cannot contract a 2nd time. I am a 40 yr old woman in genaral good health. 5 1 , 140 lbs. With no real family history of diabetes or heart disease, although I do not have medical history on my father s side. Is there something basic that I am missing? Previous visits to the doctor have always come up without an answer so I have not returned on this issue for many years. I did have pneumonia often as a child, partially due to two smokers in the home. I may have scar tissues on the lungs but I am not having breathing issues with the sleepiness.