Though almost all of us know what it’s like to be a bit behind on our sleep, those who suffer from chronic insomnia understand how truly miserable an experience it is not to be able to sleep when you want to, and what an important aspect of our lives sleep is. Though the people in insomniacs’ lives have likely never experienced the physical impact of going days without sleep at all they may well have witnessed the end result. Getting enough sleep is a true biological need, and its importance becomes very evident when that need is not met. True sleep deprivation has a distinctive set of symptoms that affect sufferers both mentally and physically. Among the first signs that a person is in need of sleep is a marked change in their mood and their ability to react normally. People who are badly in need of sleep tend to appear to be grumpy and short-tempered. They are not as likely to see the humor in a situation and may be much more prone to tears of sadness, frustration or anger. Just as adults are able to tell that a young child is in need of sleep by the quickness o their tears, in adults the physical condition of being exhausted seems to exacerbate every emotional situation, making people feel much more vulnerable or on edge. In addition to being more emotional, the hypersensitivity that sleep deprivation creates can lead to heightened feelings of paranoia – this is particularly true after about three days without sleep. People who are sleep deprived are also likely to exhibit signs of a severe malaise that impacts their willingness or interest in participating in any type of activity, even those that normally bring them satisfaction or happiness. This lack of motivation generally impacts basic tasks – they are still able to do them physically, but they lose their motivation to do so. Though some sleep deprived people may exhibit symptoms common to specific mood disorders, they rarely actually suffer from psychiatric changes – once they get the sleep they need, they return to their normal behaviors and mental state. In addition to losing interest in performing basic rituals and tasks, people who are sleep deprived may also lose interest in participating in any kind of planning. Anything that involves looking into the future seems completely beyond their comprehension or interest, as though anything other than the immediate moment no longer has any importance. Unfortunately this phenomenon translates into a lack of interest or awareness in their immediate surroundings – this is one of the reasons that it is so important that those who are suffering from severe insomnia or sleep deprivation not operate heavy machinery or be put into positions where other’s lives may be jeopardized by their actions or decision making. Their inability to prioritize can be life threatening both to themselves and to those around them. Short-term memory suffers profoundly from lack of sleep. Sleep plays an important role in our ability to remember what has happened in the previous 24 hour time period, and when the body is cheated of its needed sleep it is as though the memory’s filing system is thrown into disarray. Physically, the impact of lack of sleep can be seen in almost all systems of the body and how it functions. Vision becomes blurry so that reading or writing become extremely difficult and important processes such as depth and distance perception are impacted. Reaching for objects can actually become a challenge unless extreme concentration on the specific object is used – simple hand-eye coordination movements become difficult. After approximately three days without sleep those who are sleep deprived may begin to hallucinate and see things that are not actually there. One of the most interesting but vexing aspects of sleep deprivation is the impact that lack of sleep has on the body’s sensitivity to pain. Just as we seem to be more high-strung emotionally and more likely to have our feelings hurt, those who go for long periods without sleep have been shown to be more sensitive to the physical, and will experience certain sensations as painful that do not evoke the same response when they have had enough sleep. The sensation of something as simple as a blood pressure cuff that is seen as only a bit uncomfortable to a well-rested person, may be reported as unbearable by the same person who has gone a few days without sleep. This fact has raised important questions about those who suffer from chronic pain and who report being unable to sleep as a result: does the pain create the lack of sleep, or does the lack of sleep create the pain (or make it worse)? Other studies involving sleep have shown that those who suffer from chronic sleep loss are much more likely to be obese: for whatever reason, lack of sleep tends to increase our appetite. Interestingly, lack of sleep has the same impact on the desire to have sex, and some sleep researchers have theorized that both the desire to eat and to have sex are linked to our evolutionary survival instinct – perhaps the body recognizes lack of sleep as a threat to which we need to respond. Looking at the marked impact that lack of sleep can have on our physical and mental well being, it should come as no surprise that scientists have found that those who get the least sleep also are the most likely to die at a younger age. There is a direct link between our sleep patterns and our longevity; interestingly, this is true both for those who get too little sleep and for those who sleep overly long. Sleeping the appropriate number of hours that we need on a regular basis is considered to be one of the top things that we can do to have a positive impact on our health, along with exercising, eating right, limiting alcohol intake and not smoking.