What if Lady Bertram wasn't just indolent and lazy?

What if she suffered from chronic fatigue syndrome? In this scene in Mansfield Park, Lady Bertram bas nodded off to sleep between 10-11, when Edmund and Julia walk into the drawing-room. Edward looks around for Fanny, who was on the sofa nursing a headache:

"While Fanny cut the roses," Brock. Image @Molland's. In the alcove sits Lady Bertram
with pug on her lap.

"Go out! to be sure she did," said Mrs. Norris: "would you have her stay within such a fine day as this? Were not we all out? Even your mother was out to-day for above an hour."

"Yes, indeed, Edmund," added her Ladyship, who had been thoroughly awakened by Mrs. Norris's sharp reprimand to Fanny; "1 was out above an hour. I sat three quarters of an hour in the flower garden, while Fanny cut the roses, and very pleasant it was, I assure you, but very hot. It was shady enough in the alcove, but I declare I quite dreaded the coming home again."

"Fanny has been cutting roses, has she?"

"Yes, and I am afraid they will be the last this year. Poor thing! She found it hot enough; but they were so full blown that one could not wait." - Mansfield Park, Jane Austen, 

The morning after Fanny's ball for Fanny, when her brother William must leave, Jane Austen  describes Fanny's state of mind and her conversation with her aunt:

It was a heavy, melancholy day. Soon after the second breakfast, Edmund bade them good-by for a week, and mounted his horse for Peterborough, and then all were gone. Nothing remained of last night but remembrances, which she had nobody to share in. She talked to her aunt Bertram— she must talk to somebody of the ball; but her aunt had seen so little of what had passed, and had so little curiosity, that it was heavy work. Lady Bertram was not certain of any body's dress or any body's place at supper, but her own. "She could not recollect what it was that she had heard about one of the Miss Maddoxes, or what it was that Lady Prescott had noticed in Fanny: she was not sure whether Colonel Harrison had been talking of Mr. Crawford or of William, when he said he was the finest young man in the room; somebody had whispered something to her,— she had forgot to ask Sir Thomas what it could be." And these were her longest speeches and clearest communications: the rest was only a languid "Yes — yes — very well — did you? did he ? — I did not see that — I should not know one from the other." This was very bad.

A little later, Lady Bertram says:

The evening was heavy like the day:— "I cannot think what is the matter with me," said Lady Bertram, when the tea-things were removed. "I feel quite stupid. It must be sitting up so late last night. Fanny, you must do something to keep me awake. I cannot work. Fetch the cards, — I feel so very stupid."

One can only conclude that Lady Bertram suffers from indolence, boredom, stupidity, or chronic fatigue, or a combination of all four. What do you think?