Are your hormones in tune? Mounting evidence suggests that exposure to light at night -- whether you're asleep or awake -- might play a crucial role in cancer, diabetes, and obesity. The World Health Organization classified "circadian disruption" as probably carcinogenic, and light at night is considered by some to be an endocrine disruptor that may affect melatonin, cortisol, ghrelin, leptin, and testosterone. "Most people think, and the drug companies want you to think, that waking up at night is bad for you," says Richard Stevens, ., a cancer epidemiologist at the University of Connecticut health center. But that's not the case, he says -- it's exposure to light at night that's the problem. "If you wake up at night, as most of us do, that is a period of quiet wakefulness -- stay in bed, in the dark, and enjoy it," Stevens suggests.
There are also many synthetic sex steroids. Synthetic androgens are often referred to as anabolic steroids . Synthetic estrogens and progestins are used in methods of hormonal contraception . Ethinylestradiol is a semi-synthetic estrogen. Specific compounds that have partial agonist activity for steroid receptors , and therefore act in part like natural steroid hormones, are in use in medical conditions that require treatment with steroid in one cell type, but where systemic effects of the particular steroid in the entire organism are only desirable within certain limits. 
Information from the Nurses' Health Study indicated that the combination of estrogen and androgen used to treat hypoandrogenism could increase breast cancer risk. However, other studies indicated androgens may decrease breast cancer risk. Follow-up studies on the Women's Health Initiative found women who received estrogen and no progestogen showed a significant decrease in cardiovascular disease (CVD) and breast cancer. This has caused a reconsideration of androgens added to estrogens. Still, the FDA requires demonstration of CVD and breast cancer safety for any product containing androgens or estrogen plus an androgen; that has not been done.