Do you think that claiming exhaustion is a valid defense for failing to follow established policies and procedures?

Exhaustion is not a valid defense.

A healthcare provider's first duty is to protect the patient's health and safety. If health professionals are too tired to perform duties effectively, the onus is on them not to practice under such circumstances. When people are overly tired they can make careless mistakes and faulty decisions, thus imperiling patient safety.

Unfortunately, taking oneself off duty is not always easy to do when staff shortages exist and when judgement may be impaired by exhaustion. As the nurse mentioned, she believed that she would have further burdened her colleagues. The culture of running healthcare on heroism – in which everyone is expected to do more with less – where staff stretch themselves to the limits and beyond - mitigates against staff showing weakness of any kind.