No, nervous and sluggish are not synonyms.
anxiousness, disquiet, panic
The word that means the opposite of nervous is "calm." While nervousness is characterized by anxiety and agitation, calmness reflects a state of tranquility and composure. Other synonyms for calm include relaxed and serene.
panicscaredworried
A term that can be used for a nervous fit is an "anxiety attack" or "panic attack." These are characterized by feelings of intense fear or panic, physical symptoms such as rapid heartbeat and sweating, as well as a sense of losing control. It is important to seek support and treatment if experiencing frequent anxiety or panic attacks.
Anxious or jittery can be synonyms for nervous.
affliction , anguish , anxiety
Anxiety, uncertainty
scared, frightened, nervous, terrified, shaken, startled, fearful, cowardly, reluctant.
nervous, antsy, edgy
anxiety, worry, unease, apprehension
fux, inconvenience, anxiety, trouble, problem