According to news reports, Rihanna is apparently under a 24-hour health watch after she had a backstage meltdown in Ireland.

The 23-year-old singer is in the middle of a 10-month, 101-day tour, so it would come as no surprise that she’s exhausted. After her November 25th concert was nearly canceled, Rihanna Tweeted, “so light-headed! WTF!!!!”

If stress is indeed what is plaguing Rihanna, it can manifest in a number of ways. The Mayo Clinic reports that common effects of stress include headaches, chest or muscle pain, tiredness, upset stomach, trouble sleeping and even a change in sex drive. And stress can also increase anxiety, restlessness, feelings of anger, sadness and make you less motivated to do things or less able to focus.

Here are pictures from Rihanna’s performance in London on December 1st.

Photos: Fame