Dementia
Sedatives and hypnotics should be avoided in people with dementia, according to the medication appropriateness tool for co‐morbid health conditions in dementia criteria. The use of these medications can further impede cognitive function for people with dementia, who are also more sensitive to side effects of medications. Amnesia
Sedatives can sometimes leave the patient with long-term or short-term amnesia. Lorazepam is one such pharmacological agent that can cause anterograde amnesia. Intensive care unit patients who receive higher doses over longer periods, typically via IV drip, are more likely to experience such side effects. Additionally, the prolonged use of tranquilizers increases the risk of obsessive and compulsive disorder, where the person becomes unaware whether he has performed a scheduled activity or not, he may also repetitively perform tasks and still re-performs the same task trying to make-up for continuous doubts. Remembering names that were earlier known becomes an issue such that the memory loss becomes apparent. Disinhibition and crime
Sedatives — most commonly  alcohol but also GHB, Flunitrazepam (Rohypnol), and to a lesser extent, temazepam (Restoril), and midazolam (Versed) — have been reported for their use as date rape drugs (also called a Mickey) and being administered to unsuspecting patrons in bars or guests at parties to reduce the intended victims defenses. These drugs are also used for robbing people. Statistical overviews suggest that the use of sedative-spiked drinks for robbing people is actually much more common than their use for rape.
Malcolm Lader at the Institute of Psychiatry in London estimates the incidence of these adverse reactions at about 5%, even in short-term use of the drugs. The paradoxical reactions may consist of depression, with or without suicidal tendencies, phobias, aggressiveness, violent behavior and symptoms sometimes misdiagnosed as psychosis. Dangers of combining sedatives and alcohol
Sedatives and alcohol are sometimes combined recreationally or carelessly. Since alcohol is a strong  depressant that slows brain function and depresses respiration, the two substances compound each others actions and this combination can prove fatal. Worsening of psychiatric symptoms
The long-term use of benzodiazepines may have a similar effect on the brain as alcohol, and are also implicated in depression, anxiety, posttraumatic stress disorder (PTSD), mania, psychosis, sleep disorders, sexual dysfunction, delirium, and neurocognitive disorders (including benzodiazepine-induced persisting dementia which persists even after the medications are stopped). As with alcohol, the effects of benzodiazepine on neurochemistry, such as decreased levels of serotonin and norepinephrine, are believed to be responsible for their effects on mood and anxiety. Additionally, benzodiazepines can indirectly cause or worsen other psychiatric symptoms (e.g., mood, anxiety, psychosis, irritability) by worsening sleep (i.e., benzodiazepine-induced sleep disorder). Like alcohol, benzodiazepines are commonly used to treat insomnia in the short-term (both prescribed and self-medicated), but worsen sleep in the long-term. While benzodiazepines can put people to sleep, they disrupt sleep architecture: decreasing sleep time, delaying time to REM sleep, and decreasing deep slow-wave sleep (the most restorative part of sleep for both energy and mood).