Why Sleeping Pills Are Considered the Number 1 Most Dangerous Drug?
Sleeping pills - (zolpidem (e.g., Ambien), temazepam (e.g., Restoril), eszopiclone (e.g., Lunesta), zaleplon (e.g., Sonata), other benzodiazepines such as triazolam (e.g., Halcion) and flurazepam (e.g., Dalmane), barbiturates, and sedative antihistamines such as diphenhydramine (e.g., Benadryl).
Sleeping pills may seem helpful and even innocuous; however, in a study of over 10,000 patients who took sleeping pills and over 20,000 matched patients who did not take sleeping pills the patients who took sleeping pills died 4.6 times as often during follow-ups averaging 2.5 years. Patients who took higher doses (averaging over 132 pills per year) died 5.3 times as often. Even those patients who took fewer than 18 pills per year had very significantly elevated mortality, 3.6 times that of patients who took no hypnotics.” 
In addition, sleeping pills have been shown to cause cancer in animal studies and there is evidence that sleeping pills cause cancer in people. According to Daniel F. Kripke, M.D. author of The Dark Side of Sleeping Pills Mortality and Cancer Risks, Which Pills to Avoid and Better Alternatives, “I first became interested when I saw the work of Dr. E. Cuyler Hammond at the American Cancer Society. In 1975, I went to visit The American Cancer Society, starting a collaboration which lasted for many years. American Cancer Society data from over 1 million people showed that use of sleeping pills was associated with more deaths within 6 years, but insomnia by itself was not associated with any death risk.” 
As of January, 2012, there were 24 published studies of the mortality risks of sleeping pills. Of the 22 studies which reported either greater or lesser mortality associated with sleeping pills, 21 studies showed that people taking sleeping pills died at an earlier age. (The 22nd study found no mortality risk of sleeping pills but did find sleeping pill usage associated with increased cancer deaths.)
A strange new finding from researchers at Scripps Clinic is that people who take sleeping pills such as eszopiclone, zaleplon, and zolpidem have about a 44% higher risk of developing infections which include sinusitis, pharyngitis, upper respiratory tract infections, influenza, herpes, and so forth. Although there has been essentially no discussion of this risk in the medical literature, it is statistically extremely convincing, based on studies which the manufacturers submitted to the FDA and some of their published controlled trials of increased risk of infection. 
Zolpidem (and probably other sleeping pills) relax the stomach sphincter and cause gastro-esophageal regurgitation. The acid irritation may lead to infection. Incidentally, acid regurgitation may also lead to esophageal cancer, which is one of the cancers most greatly increased among sleeping pill users. 
There are other dangers as well with the use of sleeping pills, especially if someone has sleep apnea. Because sleeping pills risk making sleep apnea worse, many experts recommend that people with apnea not be given sleeping pills.
A risk for the elderly includes a decreases tolerance to medication, decreased clearance of drugs due to possible kidney issues and risk of falls.
Phyllis A. Balch, CNC, author of Prescription for Nutritional Healing, writes that “people who take sleeping pills on a regular basis are 50 percent more likely to die in accidents. Drowsiness accounts for 200,000 – 400,000 automobile accidents every year, and it is responsible for two thirds of all industrial mishaps, most common among shift workers in the early morning hours.”
Another consideration according to Dr. Kripke is impairment of daytime thinking. “The side effects of the prescription sleeping pills are much like their benefits. At night, we want our brain cells to stop working (unless we need to get up in the middle of the night), so sleeping pills make the brain less active. If the sleeping pill is in the blood during the day, it will make the daytime brain less active and less functional. The problem is that no sleeping pill remains in the blood all night, impairing consciousness, and then suddenly evaporates at the moment of awakening. Besides, a large percentage of people who take sleeping pills do often get up at night, at a time when the sleeping pill could cause falls or confusion. Most of the marketed prescription hypnotics, when taken at bedtime, will remain in the blood with at least half strength when morning comes.” Sleeping pills generally make function worse the next day.