IPA: //ˌhaɪ.pər.əˈlɜːrt//
KK: /haɪpərəˈlɜrt/
Being extremely aware of your surroundings and ready to react, often due to stress or anxiety.
After the accident, she felt hyperalert and couldn't relax for days.
Hyperalert → It is formed from "hyper-" (meaning over or excessive) and "alert" (from Latin "alertus", meaning to be on the watch or attentive). The word "hyperalert" describes a state of being excessively attentive or watchful.
Think of being 'overly' ('hyper-') 'attentive' ('alert') — that's what hyperalert means.
No commonly confused words.