Well there are different possible explanations. How long has this been a problem for her? Some headeaches such as may occur with a sinus infection may occur more with LYING DOWN >> so it may be position vs the rooom as a trigger >>??
Her neck position may be a trigger so if she sleeps say with two pillows then this may cause an awkward neck position and this may be a trigger for headaches.
Mold exposures may at times be a trigger for headaches (this seems less likely with the testing that you had done)
Chemical fumes such as formaldehyde can be a trigger for some (asbestos I would think very unlikely >> this insulation material would have been cleared out long ago in most dwellings but headaches would not be an expected presentation for this really either.. )
What type headaches does she have ( sharp pain, shooting pain,throbbing in quality, steady ache??) and where does her head hurt? front to back ? one side? cheeks? eyes? these details would be helpful...
Has she seen a doctor for her headaches? This would be probably helpful if she has not yet taken that step..
I hope that this information is helpful . Let me know if you have further details or questions. I will be happy to get back with you! If my answers have been helpful and to your satisfaction then please remember to leave positive feedback. Thank You and Best Regards,
Anthony Bray MD