Then is an adverb denoting time; Than is a conjunction used in comparisons.
In the middle of the night the young woman awoke and then saw that the fire had gone out.
The previous day more firewood than ever had been carried inside, but still it ran out.
She struggled from her sleeping bag, fully clothed except for shoes; then she peered at the thermometer.
It read 34 degrees below zero, Fahrenheit, which was lower than she had ever noted.
She thought about the woodpile forty feet away, then opened the cabin door.
Her nostrils froze, then her eyes tingled more than normal.
She decided against the wood, closed the door, then crawled back into her sleeping bag.