Have you ever stayed awake all night, with insomnia, due to some health interaction? I have. Insomnia is one of the most common conditions that you can develop and it creeps up on you. In our society many people have insomnia. The definition of insomnia is an inability to sleep or constant habitual sleeplessness. Ironically enough, the more sleep you miss out on the worse your insomnia will get because eventually you will develop small amounts of brain damage which could abolish your brain's ability to effectively initiate your circadian rhythm(among other things). Your circadiam rhythm is your sleep/wake cycle and is governed by a gland in your brain called the suprachiasmatic nucleus. Let's go into this more.
The suprachiasmatic nucleus (SCN) is a small group of brain cells located in the hypothalamus that controls the circadian(sun) sleep/wake cycles and influences many physiological and behavioral rhythms such as the sleep/wake cycle.  Naturally, we are supposed to go to sleep when the sun goes down and wake up when the sun comes up. Optimally we would be going to sleep at 8 or 9 p.m. and waking up between the hours of 4 and 5 a.m. Michael Rosbash, director of the Brandeis National Center for Behavioral Genomics has stated that a person with a normal SCN will go to sleep around these hours.  Of course this may seem absurd to most of societal standards but that's just the way the physiology of the body works. He also stated that when our SCN is lesioned (damaged) it will disrupt its ability to function correctly, thus insomnia!
Insomnia will lead to more insomnia because as you stay awake all night you are slowly going to receive more and more brain damage over time. The brain goes into deep R.E.M.(rapid eye movement) Sleep between the hours of 1 and 3 a.m. where it does a lot of deep healing work from the previous day to get the nervous system ready for the next day. If you stay awake during those hours you will not get the proper brain healing and brain damage will occur. Surely we can now see and appreciate how lesions may happen in our brains from lack of sleep.
Additionally, sleeping is free medicine. It is the chief free source of healing in which growth happens. Two terms we can become familiarized with are the words 'catabolic and 'anabolic'. Catabolic means you are breaking down (such as muscle cells that get broken down from hard labor) and anabolic means that you are growing. Anabolism happens mostly when we sleep properly combined with a proper diet. What you want is a body that is naturally growing and healing when catabolism occurs. Losing sleep will make you go catabolic whereas getting to bed on time will make you anabolic. This is why getting to bed on time is so important.
Lack of sleep can cause irritability, mental/physical fatigue, aggression, anxiety, depression and even weight gain. A lot of problems can occur due to lack of sleep and these are just a few of them. I do not recommend taking over the counter melatonin or synthesized vitamins as they are welcomed with a slight immune response once they enter the body due to their synthesized nature. Many holistic remedies are available to help us with getting to bed on time and help to induce deep sleep especially for those of us who have anxiety. These include herbs such as Chamomile, Passionflower, Catnip, Damiana, Valerian root and St. John's wort. You will have to experiment with yourself with each one to determine what works best for you. I recommend taking these in tea form whenever possible and buying organic whenever possible.
 video presentation: Understanding Circadian Rhythms: Understanding Sleep Disorders; youtube.com