Are you ok with white noise while you're sleeping and air flowing in the room? If you're ok with those things, run it while you're at home and sleeping. If you go to work during the day turn it off then, and turn it back on when you get home. It should rapidly clean up the air in a small bedroom.
The only real issue is any continual air flow into the room. There will be a big impact from what kind of air system you have in the greater building. For example, central air without a good filter on that system will make your fan-filter's job a lot harder.
The filters are relatively cheap to replace and will last a long time filtering a small bedroom. I get a solid year out of the filter on my central air system and it's filtering an entire home (non-smoking, no pets). Outside of the small electrical cost or annoyance from having the fan running, there's no reason not to run it very frequently if you derive a benefit. If you don't desperately need purified air for eg allergy purposes and your small bedroom isn't receiving inbound air (eg from a central air system), run it for 20-30 minutes, a few times per day, and that should easily do the job. If that's a hassle, just let it run more often than not.
The only real issue is any continual air flow into the room. There will be a big impact from what kind of air system you have in the greater building. For example, central air without a good filter on that system will make your fan-filter's job a lot harder.
The filters are relatively cheap to replace and will last a long time filtering a small bedroom. I get a solid year out of the filter on my central air system and it's filtering an entire home (non-smoking, no pets). Outside of the small electrical cost or annoyance from having the fan running, there's no reason not to run it very frequently if you derive a benefit. If you don't desperately need purified air for eg allergy purposes and your small bedroom isn't receiving inbound air (eg from a central air system), run it for 20-30 minutes, a few times per day, and that should easily do the job. If that's a hassle, just let it run more often than not.