This is a fascinating animation explaining the role of natural killer cells which are a crucial part of our immune system. What I notice from listening to it is the explanation of their role in fighting cancer. Specifically that most cancer creating cells are caught and neutralised within 24 hours by these killer cells.
It then seems very straightforward to me to argue that when we’re extremely tired it would take longer to neutralise these cancerous cells because our immune system would be weaker. Hence ensuring we get enough rest and recuperation to keep a strong enough immune system would be key to fighting cancer and all other diseases.