Sedative–hypnotics: useful medicines with a narrow safety margin
Sedatives reduce anxiety or agitation; hypnotics promote sleep. Many agents do both depending on dose. They are useful for carefully selected short-term indications, but can impair breathing, cognition, balance and driving—and can cause dependence or dangerous withdrawal. Non-drug sleep treatment and treatment of the cause of insomnia should come first whenever possible.
Learning outcomes: compare the major classes; select a short, safe course when indicated; state common adult dose ranges; recognise overdose and withdrawal; and avoid hazardous combinations.
Essential dose warning
Use current local guidance and the exact product label. The table gives common adult teaching doses, not a prescription. Older/frail adults, hepatic disease, respiratory disease, pregnancy, concurrent opioids/alcohol and sleep apnoea often require a different choice or no sedative at all.
1. Classes and mechanisms
| Class | Examples | Main action | Clinical implication |
|---|---|---|---|
| Benzodiazepines | Diazepam, lorazepam, temazepam, midazolam | Positive allosteric modulators at GABAA; increase the frequency of chloride-channel opening in the presence of GABA. | Anxiolysis, sedation, anticonvulsant and muscle-relaxant effects; dependence and respiratory depression are major concerns. |
| Z-drugs | Zolpidem, zopiclone | Act at GABAA benzodiazepine receptor sites with relative hypnotic selectivity. | Short-term insomnia treatment; still cause falls, next-day impairment, complex sleep behaviours and dependence. |
| Barbiturates | Phenobarbital, thiopental | At GABAA, prolong chloride-channel opening; at high concentration can directly depress CNS activity. | Greater overdose danger and enzyme induction; limited routine hypnotic role but important in seizures/anaesthesia. |
| Other sedating medicines | Antihistamines, antipsychotics, melatonin agonists | Different mechanisms. | “Non-benzodiazepine” does not mean harmless; assess anticholinergic, metabolic, cardiovascular and fall risks. |
2. Rational indications
First assess duration, sleep pattern, caffeine/stimulant use, depression/mania, pain, withdrawal, thyroid disease, depression, trauma, domestic safety and obstructive sleep apnoea. For insomnia, use stimulus control, a regular wake time, exercise, reduction of late caffeine/alcohol and cognitive behavioural therapy for insomnia where available. A hypnotic should be short-term, goal-directed and reviewed early.
- Acute severe insomnia: a short course only after addressing precipitating causes.
- Acute seizures/status epilepticus: benzodiazepines are emergency medicines, used by protocol with airway and respiratory monitoring.
- Alcohol withdrawal, procedural sedation, acute severe agitation: specialist/protocol-directed use; these are not routine “sleep tablet” situations.
3. Common adult dosing examples
| Medicine / use | Teaching dose range | Critical safety point |
|---|---|---|
| Temazepam for short-term insomnia | Common usual adult dose 15 mg orally at bedtime; some need 7.5 mg and some labels allow 30 mg. In adults ≥65 years, 7.5 mg is a common cautious starting dose. | Use the lowest effective dose and a short course. Do not combine with alcohol, opioids or other sedatives without specialist risk assessment. |
| Zolpidem immediate-release for sleep-onset insomnia | Take once immediately before bedtime only when 7–8 hours remain for sleep. Many labels start women at 5 mg, men at 5–10 mg; maximum 10 mg/night. | No repeat dose during the same night. Next-day impairment and complex sleep behaviours can occur; avoid driving if impaired. |
| Diazepam for selected acute anxiety/muscle spasm/withdrawal indications | Regimens vary greatly by indication and patient. Use local protocol; avoid teaching it as a routine long-term anxiety medicine. | Long half-life and active metabolites: accumulation, falls and prolonged sedation are common in older adults and liver disease. |
| Lorazepam for acute seizures/agitation | Emergency dose, route and repeat-dose limit must follow the local resuscitation/status epilepticus protocol. | Give only where airway, oxygenation and ventilation can be monitored; respiratory depression may be delayed when other depressants are present. |
| Phenobarbital | Use only for a clearly defined indication and protocol-directed loading/maintenance plan. | Major CNS/respiratory depression, enzyme induction and long half-life make casual dosing unsafe. |
4. High-risk groups and interactions
| Situation | Why risk rises | Practical response |
|---|---|---|
| Opioids, alcohol, gabapentinoids or other sedatives | Additive respiratory and CNS depression. | Avoid combinations where possible; if unavoidable, document rationale, use the minimum dose and arrange close monitoring. |
| Older/frail patient, falls, delirium or dementia | Ataxia, confusion and cognitive impairment increase injury risk. | Prefer non-drug approaches; if used, start lower, prescribe briefly and review urgently. |
| Obstructive sleep apnoea, COPD or hypoventilation | Reduced respiratory reserve; sedatives can worsen nocturnal hypoxaemia. | Usually avoid or seek specialist advice; never use an unsupervised dose to “treat” breathlessness. |
| Pregnancy/lactation | Fetal/newborn sedation and withdrawal issues vary by medicine and timing. | Use specialist obstetric/psychiatric guidance. |
| Liver impairment | Reduced metabolism and accumulation, especially with long-acting agents. | Choose carefully, lower dose where appropriate and reassess frequently. |
5. Dependence and withdrawal
Regular benzodiazepine or Z-drug exposure can lead to tolerance and dependence. Abrupt cessation may cause rebound insomnia/anxiety, tremor, sweating, perceptual disturbance, agitation, seizures or delirium. Do not simply stop long-term therapy. Make an individualised, slow taper with one prescriber, regular review and psychological/non-drug support. The taper rate must respond to dose, duration, comorbidity and withdrawal symptoms.
Overdose: do not be falsely reassured by sleepiness
Assess ABCDE, respiratory rate, oxygen saturation, consciousness, glucose, temperature and co-ingestants. Give oxygen/ventilatory support as needed and seek toxicology/critical-care input. Flumazenil can precipitate seizures and withdrawal in dependent patients or mixed overdoses; it is not a routine “wake-up” antidote. Supportive care and airway protection are often the correct priorities.
6. Counselling checklist
- Use only the prescribed dose, at the prescribed time; never “top up” after a poor night.
- Do not drink alcohol or use recreational drugs; check cough/cold and pain medicines for sedatives.
- Do not drive, operate machinery or make safety-critical decisions while drowsy or the next day if impaired.
- Keep treatment short and attend review; report falls, memory problems, unusual sleep behaviours, low mood or breathing problems.
- Do not stop a regular long-term sedative abruptly without a taper plan.
7. OSCE station
For a patient requesting “sleeping tablets,” ask about insomnia duration, sleep routine, caffeine/energy drinks, alcohol and drugs, pain, depression/mania, suicidality, snoring/apnoea, pregnancy, driving and existing sedatives. Explain non-drug treatment first. If a short course is justified, state the exact bedtime plan, duration, no-alcohol/no-opioid rule, driving advice and early review.
