Assuming a game speed of "slow," a single villager, and no way of getting new food...how long (in hours), would 1100 pieces of food last? This is more me wondering about how long food lasts than anything else, so show your work ^^ (/jk)

In a more practical, estimate-based version of this: should I risk not pausing this particular village when I go to sleep from 11PM to 7-or-8 AM?

I wouldn't risk not pausing this village overnight. Please let us know how long your village(r) lasts. Is this some kind of study you are performing? Is that why there is "no way of getting new food" when there are food sources?

In my estimate, you could leave a tribe of fewer than 10 villagers, on slow, overnight. On slow, 1000 food should last that long, plus you know they can survive with zero food for quite a long time. I leave my game on overnight all the time, and though sometimes I come back to find them getting a bit desperate, usually they're fine.

If there is any food (even a tree regenerating a little bit), any villager with some farming skill will go get it.

You can backup your game and then you will not be risking anything, since if they die you can restore the backup. Even if you don't have a backup, you can save them even if you open the game and find every last one of them has died.

I have hard numbers for you. 1000 food, with 10 villagers and one tree, should last you just over four hours, at normal speed. Leaving your village on slow overnight changes this to 8.06 hours, in which case they'll last 'til morning. However, if you have a full grove, you should be able to last another two hours - six hours normal, ten hours slow. (Risking a death or two, but the tribe should live) My earlier statement elsewhere that they'll support 11.7 villagers indefinitely seems incorrect; don't know what I was smoking. I'll recheck that math another day - I'll be out all day today.

Each villager, as far as I can determine, eats around 30 food per hour. The tree regenerates 111 food every three hours.
Assuming a 9-hour night, 1,433 ((1,100 + (111 * 3)should last just over five hours. However, five hours leaves only time for the tree to regenerate once, so we have to use 1,211 in the equation instead of 1,433, and the result changes to four hours and change.

As a final recommendation, if any die, I suggest not making more. Having any children before you have more food than the first tree generally isn't a good idea, I find; if anything, I keep only a single woman parenting, so that births are staggered automatically by the nursing period.