Insomnia is inability to sleep, either a difficulty in getting to sleep, waking repeatedly or for prolonged periods, or early morning waking (EMW) after initially falling asleep. Sleep is as essential for the normal functioning of the human body as food and drink. Doctors do not completely understand why we need sleep, but they do understand what happens when we are asleep.
There are two main types of sleep – deep sleep and REM sleep. REM stands for rapid eye movements, and several times a night, the level of sleep lightens, and while the eyelids remain closed, the eyes themselves move around rapidly. It is during this stage of sleep that dreams occur, and it is the more valuable form of sleep. If a volunteer is observed, and woken every time s/he starts REM sleep, s/he will remain tired and irritable, and obtain little benefit from the sleep. REM sleep does not start until an hour or so after first falling asleep, and long periods of deep sleep occur between each episode.
Unfortunately, many sleeping tablets induce deep sleep, but tend to prevent REM sleep, so that people using them do not benefit from their sleep as much as those who sleep naturally. This is one of the reasons that doctors are reluctant to use them until all other avenues have been explored.
The amount of sleep needed varies dramatically from one person to another. Some require only three or four hours a day; most require seven or eight hours; others may need ten hours. As we age, our sleep needs change too. An infant requires 16 or more hours of sleep a day; in middle age, eight hours is normal; but the elderly need only five or six hours sleep.
The problem here is that older people may have less to occupy their days, and so look forward to the escape of eight hours sleep every night, but find they cannot obtain it because their bodies do not require that much. This is further exacerbated by the low activity levels of many elderly people, and any midday naps they take. As a result, some elderly people seek help in obtaining extra sleep from their doctors by means of sleeping pills. This is not true insomnia, merely a desire for extra sleep, above what is biologically necessary.
There are, of course, those who genuinely cannot get to sleep for a variety of reasons, and 15% of the population fall into this category.