In addition to the spiritual dangers regarding candles used in Afro-Caribbean rituals, most candles sold nowadays are not made of beeswax but of artificial waxes and colored and aromatized with synthetic chemical colors and fragrances.

Those chemicals can be harmful to our health and not only affect our respiratory function, but volatile compounds that get released from the heating of the "wax" can also affect our nervous system. Likewise, the burning of candles in an enclosed space can deplete oxygen, increase the concentration of carbon monoxide and other byproducts of combustion and lead to hypoxic hypoxia http://en.wikipedia.org/wiki/Hypoxic_hypoxia which causes some of the symptoms that Crystal described in her question, like lightheadedness and drowsiness.

If Crystal must use candles, then she should buy pure natural beeswax candles and use them outdoors or in a very well ventilated area making sure that she doesn't bread any smoke or fumes produced by them.