My mother is bipolar... IN a manic state, she would be up all night for days, rambled on and on. Some symptoms are excessive spending, (normal for some people but my mom never was a shopper so it was all out of character for her) extreme highs and lows..When she was diagnosed, it was very obvious something was wrong with her..Even her workplace called our house to tell us abiout her odd behavior at work..Maybe your MIL isn't really familiar with bipolar