Based on the context and the answer, generate a question. 

Context: I was turning and turning in bed and despite the advil I had a big headache that would not leave me alone for one moment . I have been having them for the past few days every time I get tired and every morning when I wake up . But it 's ok ... No nightmare . strange , vivid and complex dreams but no disturbing adventures for me .

Answer:

Nightmares are a frequent occurrence for them .



What may be the reason for mentioning that they did n't have nightmares ?