This is the place to post questions and discussions on usage and style. The members of the Wordwizard Clubhouse will also often be able to help you to formulate that difficult letter.
"Insomnia" is a medical condition in which a person habitually has difficulty falling asleep or staying asleep. There are plenty of idioms for sleeping well but I can't think of too many that describe not sleeping well. You could say that you "didn't sleep a wink" or that you just "tossed and turned" all night.ACCESS_POST_ACTIONS
You can be wakeful, unsettled, restless or have trouble falling asleep. You can also be counting sheep, which is often associated with insomnia. (The reference is to the traditional remedy for sleeplessness of visualizing and counting sheep jumping over a fence, the purpose of which is to bore oneself to sleep. Obviously, if you're a sheep farmer with a deep interest in the animal, this method might not work, in which case it might be better to visualize and count the particles released by a glitter bomb.)ACCESS_POST_ACTIONS