Sleep Regression. In her life?

My daughter is 2.5 years old now. Since birth, she has sleep regressions. She will wake up between 2AM and 3AM and cry & scream uncontrollably and it lasts for 30 mins. The episodes happened so often (every night, twice a week, once a week, once a month) until she becomes 18 months. Then it gradually decreased. Episodes now comes once in 4 or 5 months. During these times, We have consulted many doctors. They said it is normal and occurs due to baby is over tired. She is learning things and languages quickly and able to talk and convey what she wants. But today the episode had come after 7 months. She woke up at 3AM and cried, screamed continuously for 30 mins. And for another 30 mins she was screaming and asking for toys, play cartoons. We tried to console her in many ways but failed. After 90 mins she became normal and slept. Is this normal and will it disappear? How long she will have such sleep regressions in her life?