HYPNOTIC DRUGS 

Some people have difficulty in sleeping soundly, and one of the hypnotic drugs can give them a good night’s rest. But it must be prescribed and taken with care. 

Sleep difficulties are common and there is a great demand for drugs which will help those who suffer from such problems to have a good night’s sleep. Although no hypnotic drug produces normal sleep, some induce sleep that is nearer to natural sleep than others. But some difficulties in sleeping are not likely to be helped by hypnotic drugs.

DIFFERENT TYPES OF HYPNOTIC DRUGS 

There are various types of sleep-inducing drugs available, but they all tend to have side-effects to some degree.

CHLORAL DERIVATIVES 

Chloral hydrate was one of the earliest drugs to be used specifically as a hypnotic. The original chemical is not much used nowadays, but chloral is the main ingredient in a drug called dichloralphenazone, widely prescribed in the tablet form and especially useful to elderly people. Chloral hydrate itself is rather irritating to the stomach and even the much less irritating dichloralphenazone has to be avoided by people who have peptic ulcers or delicate stomachs. This group of drugs has an addictive effect when mixed with alcohol.

BARBITURATES 

These used to be very widely, but now that there are safer, less addictive drugs available, they are being prescribed less and less: their main use now is in injections to produce general anesthesia.

Barbiturates are significantly habit forming, even addictive, and they produce quite prolonged ‘hangover’ effects: anyone who takes them will not be at his or her best for most of the morning after a barbiturate—induced sleep. They are also dangerous in overdose.

BENZODIAZEPINES

These are safe, even in large overdose and, considering how well they work, have remarkably few side-effects, although they may cause nightmares. However, even the benzodiazepines can be habit-forming, and if they are withdrawn there may be a rebound is sleeplessness.

OTHER HYPNOTIC DRUGS  

A mixed group of non-barbiturate drugs has largely been replaced by the benzodiazepines. One drug which was popular a few years ago was a mixture of two others: a hypnotic, methaqualone, and a sedative antihistamine, diphenhydramine. It was potent and effective but very dangerous in overdose.

For children, on the rare occasions when they need a drug with some hypnotic effect, the most useful are the sedative antihistamines, including promethazine and trimeprazine, while for elderly people a safe hypnotic drug is chlormethiazole.

HOW HYPNOTIC DRUGS WORK ?

The part of the brain responsible for the cycles of sleep and wakefulness is the reticular activating system, a widely spread network of brain cells and their nerve fibers which lace up and down the brain stem (see Brain, pp 217-219), controlling the extent to which the brain is electrically active. Some drugs, such as the barbiturates, suppress the activity of considerable areas of the brain, causing hypnotic effects at low doses and complete general anesthesia at higher doses. Others, such as the benzodiazepines do not produce general anesthesia, even at very high doses.

DANGERS AND SIDE EFFECTS

The barbiturates are particularly prone to cause a hangover, and it is dangerous to drive until their effects have quite worn off because co-ordination and reflexes are significantly suppressed.

The benzodiazepines were introduced as causing very little of a hangover effect, but, in fact, one of them, nitrazepam, has this side-effect, lasting for up to hours after it is taken.

Another serious side-effect occurs in people with chronic chest complaints: many of the hypnotics, especially the barbiturates, will interfere with their breathing in the night, often to a serious extent, and so it is best for them to avoid the use of all hypnotics.

Some people are allergic to certain drugs in the hypnotic group. It is not usually possible to predict which one will cause the allergic reaction, but if a person has it to one drug in a particular group of hypnotics, he or she will probably be allergic to chemically similar drugs.

The barbiturates can make people—particularly if they are elderly—feel confused, and this can be physically dangerous because it may cause falls. Another problem, again especially of the barbiturates but also of the chloral derivatives, is interaction with other drugs which a person may be taking. It is important for a doctor to know whether a patient is taking a hypnotic drug before prescribing any others.