Lyrics:
It's been a hard day's night
And I've been working like a dog
It's been a hard day's night
I should be sleeping like a log

But when I get home to you
I find the things that you do
Will make me feel all right

You know I work all day
To get you money to buy you things
And it's worth it just to hear you say
You're gonna give me everything

So why on earth should I moan
'cause when I get you alone
You know I feel okay

When I'm home
everything seems to be all right
when I'm home
feeling you holding me tight, tight

Yeah, it's been a hard day's night
And I've been working like a dog
It's been a hard day's night
I should be sleeping like a log

But when I get home to you
I find the things that you do
Will make me feel all right, Oh!

So why on earth should I moan
'cause when I get you alone
You know I feel okay

When I'm home
Everything seems to be all right
when I'm home
feeling you holding me tight
all through the night

Yeah, it's been a hard day's night
And I've been working like a dog
It's been a hard day's night
I should be sleeping like a log

But when I get home to you
I find the things that you do
Will make me feel all right
You know I feel all right
You know I feel all right

Documentation

A Hard Days Night was released as a single in the UK on July 10, 1964.  It appeared on the LP A Hard Days Night.

The title was taken from an expression Ringo used to say. "
This was the title song to the first of 5 Beatles movies. It got 2 Oscar nominations and was a hit with critics and audiences. 
When the deal was made to make the movie, The Beatles had not yet caught on in America and there were fairly low expectations for the film, as The Beatles were thought of as a fad that would soon pass. By the time filming began, The Beatles were huge and it was clear that a lot of people would see the movie. The studio considered putting more money into the film, but they decided to stick with the original modest budget. In order to save money, it was shot in black and white. 
The movie presented The Beatles as 4 distinct personalities, which changed the way they were marketed. Previously, they were always presented as a unified group, but it became clear that fans loved seeing their differences and began to associate with them individually. The concept of focusing on individual personalities in a band continues to this day, as groups like The Spice Girls and The Backstreet Boys are marketed with a focus on the various traits of the members, allowing fans to get to know them better. 
This was the last song in the movie soundtrack to be composed.
John Lennon sang lead. Paul McCartney sang the middle sequences. 

Written and recorded in a little more than 24 hours. It had to be done quickly when film name was changed from "Beatlemania!" to "A Hard Day's Night." 

This song has been covered by The Chipmunks, Goldie Hawn, Billie Joel and Peter Sellers.

Rick Springfield performed this song in Atlantic City, NJ on 7/23/04.  Someone had a stuffed dog that played the song, so he picked up on it from there.