This is a great question, and I wish more people were interested in how the biological clock works.
As a night owl, you basically get jet lag every day.
Jet lag means that your internal, biological clock is still adjusted to the sunrise/sundown times of another time zone, because you traveled faster than about 1 hour of timezone difference per day, i.e. per jet - that's why it's called jet lag.
There is no discipline to recovering from jet lag. Depending on the direction and the personal biological clock (they're all slightly different) it takes roughly 1 day to recover 1 hour of jet lag. So the craziest you can get is 12 hours off, which will take a week and a half to recover from.
Imagine your internal clock like a clock that you can only change the time on by about an hour per day. If you bring it to a timezone 3 hours away, you'll need to turn it by 1 hour for 3 days in a row.
"Easy" jet lag (e.g. US coast to coast) is about 3 hours, and so will only take a few days. Plus, you can miss 1-2 hours of sleep for one night and not feel that different - so it's easy to "power through" or not notice the jet lag.
Longer jet lags, like from traveling from the US to Asia, will be much more noticeable, and will often take a week or even longer to recover from. This is where you get people waking up at 2am unable to get back to sleep, and drop like a rock when the afternoon comes around.
It is slightly easier for most people to delay their sleep than to pull it forward, because the typical person's circadian rhythm is a bit longer than 24 hours. So flying from the East Coast to the West Coast results in slightly less jet lag than the other way around for most people, or at least they're able to recover slightly faster.
For night owls, if they would usually wake up at 10am and the sun comes up at 6am where they live, but really they have to wake up at 8am, they basically have a 2 hour jet lag every day. It's as if they're flying across 2 time zones every day.
This night owl will never "recover," because there isn't typically ever a sunrise at 4am at the place, which would trigger that person's circadian rhythm to wake up at 8am. You can try using tricks like light boxes (very powerful lights) to simulate the sunrise, but most commercial models are not particularly effective.
I can move my rhythm about 30 minutes forward using a commercial light box. But it gives me headaches, which I don't get from the sun. There was a post recently here on HN where somebody built his own, very bright light simulator by using LED strips. These were about 5x more powerful than the commercial light boxes, if I remember it right. He was using it to treat seasonal depression in the winter, but it should work for adjusting the circadian rhythm as well.
So these people don't just "believe" themselves to be condemned to being a night owl or early bird. It is relative to the sun, and it is malleable to a degree, but only to a degree.
As a night owl, you basically get jet lag every day.
Jet lag means that your internal, biological clock is still adjusted to the sunrise/sundown times of another time zone, because you traveled faster than about 1 hour of timezone difference per day, i.e. per jet - that's why it's called jet lag.
There is no discipline to recovering from jet lag. Depending on the direction and the personal biological clock (they're all slightly different) it takes roughly 1 day to recover 1 hour of jet lag. So the craziest you can get is 12 hours off, which will take a week and a half to recover from.
Imagine your internal clock like a clock that you can only change the time on by about an hour per day. If you bring it to a timezone 3 hours away, you'll need to turn it by 1 hour for 3 days in a row.
"Easy" jet lag (e.g. US coast to coast) is about 3 hours, and so will only take a few days. Plus, you can miss 1-2 hours of sleep for one night and not feel that different - so it's easy to "power through" or not notice the jet lag.
Longer jet lags, like from traveling from the US to Asia, will be much more noticeable, and will often take a week or even longer to recover from. This is where you get people waking up at 2am unable to get back to sleep, and drop like a rock when the afternoon comes around.
It is slightly easier for most people to delay their sleep than to pull it forward, because the typical person's circadian rhythm is a bit longer than 24 hours. So flying from the East Coast to the West Coast results in slightly less jet lag than the other way around for most people, or at least they're able to recover slightly faster.
For night owls, if they would usually wake up at 10am and the sun comes up at 6am where they live, but really they have to wake up at 8am, they basically have a 2 hour jet lag every day. It's as if they're flying across 2 time zones every day.
This night owl will never "recover," because there isn't typically ever a sunrise at 4am at the place, which would trigger that person's circadian rhythm to wake up at 8am. You can try using tricks like light boxes (very powerful lights) to simulate the sunrise, but most commercial models are not particularly effective.
I can move my rhythm about 30 minutes forward using a commercial light box. But it gives me headaches, which I don't get from the sun. There was a post recently here on HN where somebody built his own, very bright light simulator by using LED strips. These were about 5x more powerful than the commercial light boxes, if I remember it right. He was using it to treat seasonal depression in the winter, but it should work for adjusting the circadian rhythm as well.
So these people don't just "believe" themselves to be condemned to being a night owl or early bird. It is relative to the sun, and it is malleable to a degree, but only to a degree.