Getting up in the middle of the night
Most people wake up one or two times a night for various reasons. If you find that you get up in the middle of night and cannot get back to sleep within 15-20 minutes, then do not remain in the bed "trying hard" to sleep.
Get out of bed. Leave the bedroom. Read, have a light snack, do some quiet activity, or take a bath.
You will generally find that you can get back to sleep 20 minutes or so later.
Do not perform challenging or engaging activity such as office work, housework, etc. Do not watch television.