Thank you for the input.
As there is no other symptom besides bruise, you can observe.
You can let her sleep.
You need to observe a few symptoms, as you are probably aware.
Nausea or vomiting, confused appearance, seizure, weakness of a limb are some of the symptoms, need to be looked for.
Any fluid discharge from nose or ear should be checked.
If she develops any such symptom, she needs to be seen in ER.
Otherwise, you can get her checked by doctor in the morning.
If she wakes up, you can apply ice to the area, ice should not be applied directly.
Pl apply after wrapping it in a towel.
I hope this information will be helpful.
If you have any query, please feel free to ask.
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Wish her healthy life.