Waking up suddenly is not bad for your health and will not cause any harm to yourself or health.
However the waking up suddenly in the middle of the night can be caused by depression and sleep disorders that you might want to see a doctor about.
There are times I wake up suddenly in the middle of the night but it doesn't happen often and usually sometimes I wake up suddenly because of a bad dream or nightmare that happens.
Then within 30 minutes to an hour I usually go back to sleep with no issue.
The reason that most people wake up suddenly from deep sleep is stress and thoughts racing in your mind which can also sometimes keep you awake and prevent some people from sleeping.
Waking up suddenly from deep sleep can also be caused by a nightmare or dream that is affecting your deep sleep.
Stress is the most common reason that makes some people wake up from deep sleep and trying to avoid that stress can help stop the sudden waking up.
Sleep disorders or even depression can cause some people to wake up suddenly from a deep sleep.
If you continue to wake up from a deep sleep suddenly then you should speak with your doctor because you might have a sleep disorder that needs treatment to help you stay asleep.
However suddenly waking up from a deep sleep is not harmful and as long as you can get back to sleep at night after waking up suddenly you should be fine.