Uh anyone else misread this as “Sheep!”? 
Wow. Then how do your kids get to wander into your bedroom in the middle of the night and ask you inane questions like “Hey mom, where do we keep the carpet cleaning spray?” or “Mom, what is the capital of Portugal? I can’t find the encyclopedia anywhere!”?
I must have grown up in a pretty privileged household. We had 24/7 Accessible Mom 
My kids have traditionally been asleep in the middle of the night.
Of course, the sound of a retching kid half way across the house with all doors shut will cause me to fly out of bed in a heartbeat. (And yes, on those occassions when it’s a Clothing Optional night, I do throw on clothes before bounding out of the room.)
Where do you live? treat it as a staycation and be a tourist in your own town.
Check out the local community college and take a class.
Plan your own girls weekend away because you don’t need to arrange for a sitter.
Have a dinner party.
Stop doing that.
Ah, see that’s where our families differ. My mom is a morning person who married a night person and ended up with 2 night people children. By the time we were in high school, she was going to bed 3 or 4 hours before us. Poor thing has just had to resign herself to the idea that her children expected her to be available even when she was asleep. What a trooper!
(btw I am not trying to be snarky, I’m trying to be funny!!)
“Staycation” - I like that word.
I’ll bet there are a million cheesy touristy things within a couple hours of where you are that you would never think to go to. Pretend you’ve never been to your home region/state/whatever is a reasonable range from your house and visit it like a tourist would. Go to the restaurant at the top of the City Hall guide book, go to that Museum of [insert thing here], etc. You never know what you’ll discover!
It took us something like 4 years before we ever went to the Warplane Museum in Hamilton, and we only went because my (now) FIL wanted to do something touristy when he came to see us. That remains my absolute favourite museum ever, and we went to see it more than once a year since. I miss it, now that I’ve moved away.
Likewise, there are probably little tourist resorts you might want to treat yourself to.
Or perhaps a makeover? Assign a budget (how much gas/food/etc will you save in a MONTH of your son not being there - you don’t have to spend money you don’t already have!), get a fashionable buddy who knows you well, and go get an awesome new haircut and wardrobe, all based on their recommendation. At worst, hair can be recoloured, it can grow back, and you can keep wearing the clothes you have. At best… well, the sky’s the limit!
I am in a similar predicament. I only have one boy, but he and dad are going to scout camp for 4 days, overnight trip. Its the first time in 10 years I’ll be alone. I want go clubbing, drink and pick up sailors, but all those fun friends are now mommies, too. Sigh.
Pedi/mani spa day, complete with massage. Check out massage schools for cheapo massages. Less than $75 and you can feel like a queen!