Lack of sleep in the short term can cause loss of concentration, irritability, sluggishness and mood swings. In the Long term, it can affect your memory, your helth will deteriorate as you body needs the sleep to help regenerate in the nigh time. You will also have problems with mood swings. When we dream, our brain processes and works through events that we don't do when awake. if this process does not happen, your mental health will eventaully deteriorate also.
AND people who get less sleep can end up overweight
, due to the fact that you might end up eating 400 calories more than usual in the day to keep your energy levels up.
take some time for yourself and try to get a good nights sleep (at least 8hrs) at least twice a week.