BTW some tasks that night owls can do while on watch.
Ammo reloading, if you have ammo reloader your night watch could be making more ammo while other sleep.
Mag loading, putting that new ammo into mags
If ammo is low, arrow making could be an important task. Straightening smoothing and fetching arrows could be done at night.
Blade sharpening and maintenance is another good task for night crew. Have people drop off their blades (knives axes etc) and then pick them up in the morning all nice and sharp.
Candle making could also be done by night watch. Dipping candles is a time consuming task but one that enables night crews to work as well as for day people to spend a little time still awake at night.

ohhh,,,,
Something I just remembered, the historical norm of sleep schedule before electric lights is a segmented sleep.
http://www.history.vt.edu/Ekirch/sleepcommentary.html
http://en.wikipedia.org/wiki/Segmented_sleep
Segmented sleep, also known as divided sleep, bimodal sleep pattern, bifurcated sleep, or interrupted sleep, is a polyphasic or biphasic sleep pattern where two or more periods of sleep are punctuated by periods of wakefulness. Along with a nap (siesta) in the day, it has been argued that this is the natural pattern of human sleep. A case has been made that maintaining such a sleep pattern may be important in regulating stress.
http://disinfo.com/2013/08/how-our-ance ... ent-shock/
In a 4-week study with 15 men living with restricted daylight hours, something strange started to happen. After catching up on their “sleep debt” – a common state of affairs for most of us – the participants began to wake up in the middle of the night:
They began to have two sleeps.
Over a twelve hour period, the participants would typically sleep for about four or five hours initially, then wake for several hours, then sleep again until morning. They slept not more than eight hours total.
The middle hours of the night, between two sleeps, was characterized by unusual calmness, likened to meditation. This was not the middle-of-the-night toss-and-turn that many of us experienced. The individuals did not stress about falling back asleep, but used the time to relax.
Russell Foster, professor of circadian neuroscience at Oxford, points out that even with standard sleep patterns, this night waking isn’t always cause for concern. “Many people wake up at night and panic,” he says. “I tell them that what they are experiencing is a throwback to the bi-modal sleep pattern.”
There is a lot more info out there on this segmented sleep, I just wanted to cover the basics here.
So us night watchers might end up getting some company in the middle of the night. Which is nice, night life might have gotten lonely. But iof people started reverting to a segmented sleep schedule some would likely come visit with the night crew, check in, talk and socialize, maybe a little midnight delight from a lovely lady
This would definitely make night watch more enjoyable.