Improving your sleep allows time for your brain to re calibrate its-self, time to balance all your hormones the messengers which control every thing you do.
In order for this to happen you need several hours sleep 7-9 hours is recommended.
Literally everything you do or suffer from is controlled by your hormones, sleep, stress, hunger, cravings, weight gain, attention, accidents. Are all controlled by your hormones.
Take weight gain if you have disrupted sleep over a long period of time, your body will begin to lose control of your body composition and drive your appetite cravings, which could lead to increased fat deposited around your body. As you gain more fat and increase your body mass; this will put increased stress on the rest of your body and so increase the risk of higher blood pressure, cardio vascular conditions, joint problems and possible developing diabetes.
Poor sleep also affects your attention and ability to concentrate due to being over tired, as it affects our ability to make decisions, this could affect accidents, inability to focus on important mental tasks like studying for example.
How do you improve your sleep
There are a number of strategies your can look into trying but start with getting into a routine like going to bed at the same time, getting up at a regular time which allows you time to have a good breakfast. When you leave for work you should feel ready for the day ahead and not ready to grab the nearest coffee shop on the way in.
Avoid stimulants like alcohol and caffeine late in the evening, these will keep you wide awake.
Try a relaxing activity to allow you brain to slow down, reading, Yoga, Thai chi and lovemaking!
Avoid late evening exercise particularly if it is intensive as this will also stimulate you to stay awake however the endorphin release from exercise will improve the quality of your sleep for the rest of the night.
Have a late evening snack something with carbohydrate in it and foods rich in Tryptophan like chicken, cheese, milk, oats, seeds etc. These will help you get off to sleep.