Good night, Sleep tight
To sleep tight is to sleep well. 'Tight' seems an odd word to use in this context. It may refer to pulling bed clothes tightly around you as you snuggle down to go to sleep but there is another explanation.
In Shakespeare's time bed frames were strung with ropes on which straw mattresses were placed. After some time the ropes would loosen, resulting in an uncomfortable bed. When pulled tight, the bed improved. Apparently there was a tool - an iron type of gadget that looked somewhat like an old clothes peg but larger - which was used to tighten the ropes.
www.takeourword.com disagrees saying ...
This explanation does seem plausible. Beds which support their mattresses on ropes did exist and are still used in some parts of the world. On the other hand, this would imply that, after you've read your child a bedtime story and kissed her on the cheek, you expect her to pop out of bed and haul on the ropes which support her mattress.
If this phrase originated 'in Shakespeare's time' then there should be some written evidence of its use from those days. After all, the writer of the original email had to get their information from somewhere. We are unable to find any example of the word tight use in regard to sleeping earlier than the late 1898. The phrase sleep tight did not appear until even later. Here's the first use we could find:
Good night, Son. Sleep tight. - Eugene O’Neill Ah, Wilderness! 1933
It seems that the word tight was used to mean "soundly" or "steadfastly", as in the expression sit tight. The phrase goodnight, sleep tight probably caught on purely because of its internal rhyme.
The original meaning is probably the Danish word kippe for a hut or an alehouse. It was first recorded in the mid 18th century as an Irish slang term for a brothel. By the latter part of the 19th century the word meant a common lodging-house for tramps and the homeless. Soon after, it changed from the place where you sleep, to the act of sleeping itself (though in Scotland the word can mean a bed). In the 20th century it shifted still further away from slang towards the modern informal or colloquial usage — to mean either a nap or a longer sleep; the idea or act of sleeping.
In the pink
In the pink signifies a state of well being; good health. The pink here has nothing to do with colour, rather with the same source as pinking scissors. They are both based on the old English pynca meaning "point", hence "peak" or "apex". Shakespeare in Romeo and Juliet (II, iv) speaks of "the pink of courtesy".
Sleep like a top
To sleep like a top is to sleep very soundly. This seems an odd way of describing a good sleep. However, the top referred to is indeed the child's toy. When it is spinning, it appears to be still. It is this apparent stillness that gave rise to the simile, first used in 1613.
Never stand when you can sit, never sit when you can lie down, never stay awake when you can sleep.
The Army and the Fire Service
To know much sleep less.
How the Biblical Land of Nod came to be associated with sleeping.
www.takeourword.com says ...
If you didn't know it is Biblical, you might assume it was originally a poetic fabrication referring to sleep. "To nod off"
The phrase Land of Nod in the Bible refers to the place where Cain went after murdering Abel (Genesis 4:16), came to be used as a pun for 'sleep' because of the obvious similarity between nodding and falling asleep.
This usage began in the mid-18th century.
The first recorded use of the phrase to mean "sleep" comes from Jonathan Swift in about 1737.