Sleeping pills and minor tranquillisers

Explains what sleeping pills and minor tranquillisers are used for, how the medication works, possible side effects and information about withdrawal.

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What are the different types of sleeping pills?

This page covers:

Overview of all non-benzodiazepine sleeping pills

Here's an overview of all the non-benzodiazepine sleeping pills currently licensed in the UK.

Some of these drugs have more than one name. You might know a drug by its generic name or its trade name (see our page about drug names for more information on this).

For detailed information about a particular drug, you can look it up in our sleeping pills and minor tranquillisers A–Z.

chloral / cloral

Sleepeaze (see diphenhydramine)

Circadin (see melatonin)

Sonata (see zaleplon)

clomethiazole / chlormethiazole

Stilnoct (see zolpidem)


Welldorm (see chloral hydrate)

Heminevrin (see clomethiazole)



Zimovane (see zopiclone)



sleep aid tablets (see diphenhydramine)


The ‘Z’ drugs

Generic name

Trade names (UK)

Forms available


Dietary considerations



  • capsules

about 1 hr

  • contains lactose

  • contains gelatin



  • tablets

about 2.4 hrs

  • contains lactose



  • tablets

about 5 hrs

  • contains lactose

The 'Z' drugs were designed to try to overcome some of the problems associated with benzodiazepines, but they act in a very similar way.

Dependence and withdrawal symptoms are just as likely to occur as with benzodiazepines.

'Z' drugs should be given:

  • for severe problems only
  • at the lowest effective dose
  • for the shortest possible time

They should be withdrawn gradually.

Guidelines on use

  • 'Z' drugs are short-acting and have little or no hangover effect
  • it’s best not to take them with (or immediately after) food, as this may make them work more slowly
  • you should not take them with alcohol
  • you should not take a second dose in one night
  • you should take them when you are ready for sleep, and not before
  • you shouldn’t normally take sleeping pills for more than three weeks, and preferably for no more than one week

'Z' drugs are better than other sleeping pills for older people because their short half-life means they are less likely to accumulate in the body and cause adverse effects.

After taking them you may be rather unsteady and clumsy if you need to get up during the night, e.g. to go to the toilet.

Confused GPs prescribed me an endless succession of sleeping tablets, increasing the dose of zopiclone then, when the effects wore off, alternating it with other 'Z' pills such as zolpidem.


All 'Z' drugs can occasionally cause a type of sleep-walking, when you may get up and do things while you are not really awake. These include:

  • dangerous activities like driving
  • eating, including inappropriate food (e.g. raw food that should be cooked)
  • having sex
  • being violent to your bed partner

When you wake up you may not remember anything about what you have done.

If anything like this happens to you, talk to your doctor about it immediately.

You should not take these drugs: 

  • if you have sleep-related breathing problems (e.g. obstructive sleep apnoea)
  • if you have neuromuscular weakness (e.g. myasthenia gravis)
  • during pregnancy or breastfeeding

The same cautions about who should take them apply as for benzodiazepines.

NICE (the National Institute for Health and Care Excellence) guidelines on the use of 'Z' drugs
  • doctors should not prescribe a sleeping pill unless non-drug treatments have been tried unsuccessfully
  • they should be prescribed only for short periods and strictly according to the licence for the drug
  • as these three drugs are very similar, the cheapest drug should be used (taking the dose needed into account)
  • if one 'Z' drug is unsuccessful, others should not be tried

In the past I have suffered manic and psychotic episodes. Being able to sleep was important in helping me recover, so the 'Z' drugs they gave me in hospital really helped.

Other non-benzodiazepine sleeping pills

These drugs are of several different types and do not form a single group. They vary in their effectiveness and general characteristics.

Generic name

Trade names (UK)

Forms available


Dietary considerations

chloral hydrate


  • liquid

more than 6 days




  • capsules

  • liquid

3.6–5 hrs

  • capsules contain gelatin


Sleep aid tablets

  • tablets

7–17 hrs

  • contains lactose



  • tablets

3.5–4 hrs

  • contains lactose



  • tablets

  • liquid

  • injection*

5–14 hrs

  • tablets contain lactose

* Promethazine injection is a prescription-only medicine and administered only by healthcare professionals in appropriate circumstances.


Antihistamines are primarily used for treating allergic reactions and conditions such as hay fever. Their main side effect is drowsiness, so they can also be used for short-term sleeping problems.

The following are available as sleeping tablets over the counter from a pharmacist without a prescription:

They are long acting and so often leave a hangover effect the following day.

They may be slow to act, and lose their effectiveness after a few days.

Antihistamines should be used with caution by:

  • men with an enlarged prostate
  • anyone with problems urinating (urinary retention)
  • anyone with glaucoma (raised pressure in the eye)
  • anyone with liver disease
  • anyone with epilepsy
  • anyone with porphyria (a rare, inherited illness)

Antihistamines should not be used during pregnancy or while breastfeeding.

The main side effects are:

Most common

more common in older people)


  • disorientation
  • dizziness
  • headaches
  • nightmares
  • restlessness
  • tiredness
  • blurred vision
  • confusion
  • dry mouth
  • excitement (especially in children also)
  • urinary retention
  • blood cell disorders
  • disturbances of heart rhythm
  • loss of appetite
  • low blood pressure
  • muscle spasms
  • sensitivity to sunlight
  • shaking
  • stomach discomfort
  • tic-like movements

If you are in doubt whether antihistamines are suitable for you, or if you are taking any other medication (including herbal remedies), you should discuss this with the pharmacist before you buy them.

Melatonin (Circadin)

Melatonin is a natural hormone produced by the pineal gland – a gland in the brain which regulates the body’s response to the 24-hour night and day cycle.

It is licensed:

  • as a supplement for insomnia
  • for adults aged 55 years and over
  • for short-term use only

It is not recommended for children and adolescents below the age of 18 (but may be used in certain circumstances).

Chloral hydrate and clomethiazole

These are old drugs which are now rarely used as sleeping pills.

Chloral hydrate and clomethiazole used to be given to children, but nowadays this is not recommended. They are not particularly useful in older people.

They should not be taken in pregnancy or while breastfeeding.

They should be used with caution for people who have a history of drug or alcohol abuse, and marked personality disorder. Contact with the skin should be avoided.


Barbiturates were used as sedatives before benzodiazepines became available. They are rarely prescribed now, so we do not give any details about their use here.

The British National Formulary (BNF) says that intermediate-acting barbiturates (available for named patients only) should:

  • be used only to treat severe insomnia that has not improved with other treatment in patients already taking barbiturates
  • be avoided in older people
  • the use of the long-acting barbiturate pentobarbital for sleep is unjustified.

This information was published in August 2016. We will revise it in 2018.

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