Many people struggle with sleeping.

Whether you find it hard to doze off, constantly wake up during the night or you can't seem to sleep at all, it can be incredibly frustrating and will play with our bodies and minds. However, a sleep expert has just explained what really happens to our bodies if we don't get enough shut eye and it's quite shocking. Matthew Walker, professor of neuroscience and psychology at the University of California and author of the book Why We Sleep wrote on Business Insider about everything that happens internally after a bad night of sleep. The first piece of information he gave us is that it effects our memory, and it's a rather scary thought. He said: "We certainly know that a lack of sleep will actually prevent your brain from being able to initially make new memories, so it's almost as though without sleep the memory inbox of the brain shuts down and you can't commit new experiences to memory." We can't remember what we actually do? The thought of not being able to make new memories is is frightening one, but to further that, it can also lead to Alzheimer's disease. "A lack of sleep will lead to an increased development of a toxic protein in the brain that is called beta-amyloid and that is associated with Alzheimer's disease because it is during deep sleep at night when a sewage system within the brain actually kicks in to high gear and it starts to wash away this toxic protein," he said. Not sleeping enough can also effect your reproductive system, as well as cancer-fighting cells. "Men who are sleeping just five to six hours a night have a level of testosterone which is that of someone ten years their senior," Matthew explained. He further wrote: "After just one night of four to five hours of sleep, there is a 70 percent reduction in critical anticancer-fighting immune cells called natural killer cells. And that's the reason that we know that short sleep duration predicts your risk for developing numerous forms of cancer." It can also affect your cardiovascular system, with Matthew writing that the day after Day Light Savings Time in Spring, there is a 24 percent increase in heart attacks. Matthew finished his piece by explaining that the "recycle rate of a human being" is 16 hours, and if we were to hit 19 or 20 hours, we'd have the mental capabilities of a drunk person.