Doctors use the term 'insomnia' to refer to any kind of poor sleep. This could mean difficulty getting to sleep in the first place; disturbed sleep, where you wake regularly for long enough to remember it; waking early and not being able to get back to sleep; or feeling tired even after an apparently good night's sleep.
This is a companion discussion topic for the original article at https://patient.info/news-and-features/understanding-the-cause-of-your-sleep-problems