Final answer:
Sleep deprivation weakens immune function by leading to immunosuppression and making individuals more susceptible to illness.
Step-by-step explanation:
Sleep deprivation has significant effects on the immune system. While short-term stress may redirect bodily resources to enhance innate immune responses, over time, lack of sufficient sleep can lead to immunosuppression.
Research shows that sleep deprivation results in decreased efficiency of the immune system, making one more susceptible to illness. This weakens immune function rather than enhancing it. Therefore, the correct answer to the question is that sleep deprivation C) Weakens immune function.