The Behavioral Activity Rating Scale (BARS) is a single-item, 7-point observation scale used to assess a patient’s level of agitation or sedation in emergency and psychiatric settings. It is based on one observed behavior rating rather than a long questionnaire.

The scale runs from:

• 1 = difficult or unable to rouse
• 4 = quiet and awake, which is the normal activity level
• 7 = violent and requires restraint.

The full 7 levels are:

1. difficult or unable to rouse
2. asleep but responds normally to verbal or physical contact
3. drowsy, appears sedated
4. quiet and awake
5. signs of overt physical or verbal activity, but calms with instructions
6. extremely or continuously active, not requiring restraint
7. violent, requires restraint.

In practice, BARS helps clinicians quickly communicate severity, monitor changes over time, and guide responses to agitation. A simple summary is:

• 1–3: sedated / underactive
• 4: normal
• 5–7: increasing agitation severity.

So, the simplest definition is: BARS is a quick bedside scale that grades observed behavioral activity from deeply sedated to violently agitated.