Harvard Health Publications discusses why benzodiazepines are frequently prescribed to older adults (including for insomnia), when their use may be justified, and other options patients have.
If they have taken one of these medicines when they were younger, most people trust that it will always be safe for them. But if you are over 65 now, you are not the same person you were in your 30s, 40s and 50s.
Older people have less blood circulating, and more fat relative to water. This means that the drug is more concentrated in their bodies, and the effect is stronger. Older people have less efficient kidneys. The liver clears drugs from the body more slowly. So drugs build up. Also, most older people take many medicines. This means there is a greater chance of drug interactions.