Title I of the ADA- Disability Law

Sallie works as a stock trader with a large well-known bank. She has been on the job for more than fifteen years and is well liked and respected in her field. As a stock trader, Sallie is required to be to work at 7:30 AM to assess the international markets before focusing her day on the NYC Stock Exchange.  Sallie is very good at what she does. However, her job is very busy and stressful. Often times she does not get a break in her day to get up from her desk until the markets close at 4:30 PM.
In April 2021 after not feeling well for about two months, Sallie was diagnosed with Chronic Fatigue Syndrome (CFS). CFS is medical condition characterized primarily by persistent fatigue. For Sallie, in addition to fatigue she also experienced muscle fatigue, joint pain and headaches. Her doctors told her that in order to keep the condition under control, she needs to: (1) have ten hours of sleep per night, (2) maintain a specific diet, and (3) limit her stress as much as possible.  Sallie knows changes need to be made in her job and that she needs to speak with her bosses. She obtains the necessary documentation from her medical providers to speak to her bosses.
1. What is the definition of disability? Does Sallie fit within it?
2. Can Sallie ask for a reasonable accommodation? 
3. If so, what kind of reasonable accommodations can Sallie ask for?
4. What might Sallie’s company argue to oppose this request?
5. How does your analysis change (if at all) given how work has changed during the COVID-19 pandemic?