This situation quite often happens when your mind is overactive either dwelling on something in the past or worrying about something in the future, mainly not being able to get back to sleep! Mindfulness can be very useful in helping us to overcome insomnia. It may sound very strange but if you have a willingness to stay awake you are much more likely to fall asleep. By having the willingness to be awake you reduce the anxiety about not being able to get to sleep.
Acceptance and letting go are two of the key concepts of mindfulness. Firstly if you are experiencing insomnia then accept that you are awake even though you want to be asleep, it is what it is! Also employ the non-striving concept of mindfulness that the goal is not to get to sleep but just to be in the present moment and focus on what you can feel in the body: the sensations of touch and pressure as the body makes contact with the bed and the pillow. This helps us to seek refuge in the body and gives us a respite from the dominant thoughts in our heads. We can then do a simple breath meditation, focusing our awareness on our breath and returning our awareness to the breath every time we notice the mind wandering back to our thoughts.
If we find that we are dwelling on the past or worrying about the future we can be aware that we have engaged in mental time travel that is pulling us away from the present moment and let go of these troublesome thoughts focusing on the here and now. Lying down on a padded mattress and letting go of our mind and body is basically what happens when you fall asleep!
If we notice that our thoughts seem to be very dominant it may help to see the thoughts as mental events in the mind rather than absolute truths! This may help us to reduce the anxiety, hopefully supporting us to get to sleep.
Finally even if you do not sleep much one night it doesn't necessarily mean that you will feel tired the next day. Many people do not sleep very well but are able to function perfectly well, especially by not focusing on any sensations of tiredness they have in the body and focusing their attention on to what is happening in the here and now.
Energy flows where your attention goes!