EEOC regulations say that a major life activity is something basic that the general population does with little or no difficulty. Examples include self-care, and tasks such as driving, walking, seeing, hearing, speaking and learning. Moreover, judges don't determine what is and what is not a major life activity by looking at individuals. Activities must be significant within the ADA and the statutory context. Tenth Circuit judges concluded that sleeping is a major life activity.
Most people do it without difficulty, although many experience sleeplessness occasionally.
It may be a component of such an activity, such as working or learning, but by itself, concentration isn't a major life activity. At this point, Pack couldn't win with concentration, but sleeplessness was still alive. It didn't live long. The court ruled that her burden of proof required showing not only her own condition of sleeplessness, but her ability to sleep compared to that of the average person. What's more, Pack had to present circumstances that would mitigate or correct her condition.