Minimise the amount of light coming in from outside.

Make sure that your outdoor lighting does not disturb your sleep. First and foremost through good blackout, but if necessary, you can also install a timer to regulate the lights so that they are not switched on at night. The reduced electricity consumption also saves you money. 
 

WHY IT HELPS:
Because the receptors in our eyes are sensitive to light even when we're asleep, sleep can be disrupted by your outdoor lighting. Any light the eyes take in during the night is interpreted by the brain as a sign that it is daytime. By having a completely dark bedroom, you ensure that you are not disturbed and risk waking up unnecessarily.