There is a very funny TV commercial where a hairy boar sits on a man's stomach and he jerks awake. He is having digestion problems because he has not followed one of the cardinal rules about how to calm down at night. That is never eat a heavy meal near bedtime.
But I also like the winding down principle as well. That is to start the calm down process an hour before bedtime. .No emails or any work on the computer. The light from the screen is bright and resembles bright sunshine so it can upset our circadian rhythms. Then we need to have pretty soft lighting and a relaxing activity like reading something. That is better than watching TV but at least if we do that, we should make sure that we are not watching exciting, fast paced action movies where there is lots of violence. Something more restful would be ideal. Listening to relaxing music is perfect as is having a nice warm drink or a bath, or both!
Then there are other more physical ways to calm down at night such as doing stretching exercises and learning deep breathing techniques so that we can get rid of some of the tension built up during the day. I like the idea where we can tense and relax each group of muscles so that at the end we are completely relaxed. Then there are some people who swear by visualizing the tension as it is lifted off the body when we are lying down. We can also picture tensions melting away as they no longer concern us.
Another way is to have white noise in the bedroom as you prepare for sleep. White noise is a mix of all possible sounds in varying frequencies which drown out all single frequency sounds. This can usually be recorded or simply turn on a fan. If the weather is hot this is a great way to cool down too as the ideal temperature for sleep is about 18 degrees Celsius. As the sense of sound is the last sense to be switched off, this helps in masking all the other sounds and helps to get us off to sleep. Avoiding stimulating activities, food and drink is also a great way to calm down at night.