Final answer:
When monitoring an older adult client who has been prescribed zolpidem for insomnia, the nurse should watch for hypotension as a known adverse effect, among others like sleep problems, agitation, and constipation.
Step-by-step explanation:
If an older adult client has been prescribed zolpidem for insomnia, the nurse should monitor the client for several potential side effects or adverse reactions. Zolpidem can cause a variety of side effects, but among the options provided, hypotension (low blood pressure) is a known adverse effect of this medication. It's important to carefully monitor the client for signs of hypotension such as dizziness, fainting, and fatigue, which can increase the risk of falls and other complications in older adults. Other side effects could include sleep problems, agitation, anxiety, and gastrointestinal issues such as constipation, but hypotension should be particularly monitored due to its potential consequences.