Why do people go to bed?

I had an infinite supply of water and 5 litres and 3 litres jars.

How would you measure exactly 4 litres in the least number of steps?

Why is the Hole below a Lock?

Solve below rebus puzzle?

The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

Do You See It?

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

Move three sticks of the spiral below to form a square.

Your mother’s brother’s only brother-in-law is asleep on your couch. Who is asleep on your couch?