Lakshman’s wife goes to sleep.(Ramayan)

http://devdutt.com/articles/ramayana/lakshmans-wife-goes-to-sleep.html

On the first night in the forest, Lakshman kept watch while Ram and Sita went to sleep. That is when Nidra, the goddess of sleep, approached him. He begged the goddess to leave him alone for fourteen years so that he could guard his brother and sister-in-law night and day. The goddess, impressed by his act of filial devotion, agreed. But the law of nature demanded that someone bear the burden of Lakshman’s share of sleep. “Go to my wife, Urmila, and inform her of the situation,” said Lakshman. Nidra went to Urmila.

Urmila bowed her head and replied, “Give me my husband’s share of sleep for fourteen years so that he can stay awake all that time without any fatigue.” 

So it came to pass that Urmila slept for fourteen years night and day while her husband stayed awake in the service of Ram and Sita.

This had an impact in the war against Ravana. Ravana’s mighty son, Meghnadh, was invincible. Only a man who had not slept for 14 years could defeat him. Thus Lakshman was able to kill him, all thanks to Urmila.