Nobody likes to wake up in the middle of the night, especially if it is because of something as simple as a door creaking open. In this sense, heavy sleepers have got it made; if their partner gets up to go to the bathroom, they can sleep right through it. So why do some people wake up just because their partner turned over in bed, but other people can keep sleeping even if their partner turns on the television?
Part of it has to do with the amount of time spent in each stage of sleep. People who spend more time in deep stages of sleep are more likely to be heavy sleepers. Since deep sleep is essential for development, young people spend more time in deep sleep stages. For this reason, young people are often heavier sleepers than older people (per Everyday Health).
Brain rhythms may also influence how deeply a person sleeps. A 2010 study (via Current Biology) found that people who produce more sleep spindles (a type of brainwave) are more likely to be heavy sleepers.
This is how to sleep more deeply
Scientists have not yet discovered a way to increase sleep spindles, but there are other ways people can make sure that they sleep more deeply. In particular, people may want to establish a sleep schedule and bedtime routine, and keep their bedroom cool. Some people may want to invest in a higher-quality mattress if their current mattress is uncomfortable. AmeriSleep also suggests using noise mufflers, eye masks, and blackout curtains to avoid being woken up by noises or light.
It is also a good idea to avoid electronics for a few hours before bed because blue wavelengths reduce melatonin, the hormone that promotes restful sleep (per Harvard Health Publishing). Alcohol should also be avoided around bedtime, since it impairs deep sleep, Dr. Rajkumar Dasgupta told Everyday Health. Instead of drinking alcohol and watching television, Everyday Health suggests taking a warm bath and reading a book.
If all else fails, you may want to talk to your doctor. It is possible that you have a sleep disorder for which your doctor may be able to provide treatment.