This may seem like a pretty easy one but any sort of noise can startle you awake and disrupt your sleep patterns. Partying neighbours, snoring, loud traffic can all be causes of noise pollution in the bedroom that can prevent you from getting much needed, restful and uninterrupted sleep.
There are a couple of easy ways to fix this issue.
The first option is to buy some quality noise cancelling headphones. A simple google search will show up plenty of options. My personal favourites are the Acoustic Sheep Headphones, extremely comfortable, great sound and not bulky. You can also play soft soothing music as you drift off to sleep.
The second option is the more cost effective solution, simple ear plugs, cheap yet very effective!