Timezones, people working late shifts, unusual sleeping schedules--there are always countless people asleep/awake no matter when you update, so I'm not all that bothered by a potential audience being asleep when I update. If you're concerned about it, try experimenting by uploading at different times and see if there's a 'trend' in views/subscribers on certain days or during a specific timeframe.
That being said, I have no schedule whatsoever besides updating daily, but lately it's been around 6-8 pm CET because it's the most convenient time for me. Sometimes I update between 6 - 7 in the morning before I leave the house. Sometimes at completely different times.