Paraldehyde is the cyclic trimer of acetaldehyde molecules. It was introduced into clinical practice in the UK by the Italian physician Vincenzo Cervello in 1882. It is a central nervous system depressant and was soon found to be an effective anticonvulsant, hypnotic and sedative. It was included in some cough medicines as an expectorant (though there is no known mechanism for this function beyond the placebo effect). Paraldehyde also has been used in the treatment of alcoholism and in the treatment of nervous and mental conditions to calm or relax patients who are nervous or tense and to produce sleep. However, this medicine has generally been replaced by safer and more effective medicines for the treatment of alcoholism and in the treatment of nervous and mental conditions.

Aprobarbital is a barbiturate derivative. Aprobarbital have been used for the short-term treatment of insomnia and for routine sedation to relieve anxiety, tension, and apprehension however, barbiturates generally have been replaced by benzodiazepines.

Melatonin (5-methoxy N-acetyltryptamine) is a hormone synthesized and released from the pineal gland at night, which acts on specific high affinity G-protein coupled receptors to regulate various aspects of physiology and behaviour, including circadian and seasonal responses, and some retinal, cardiovascular and immunological functions. Melatonin is also made synthetically and available without a prescription as an over-the-counter (OTC) dietary supplement in the U.S. Melatonin supplementation has many uses, however, it has been widely studied for treatment of jet lag and sleep disorders. Parents may consider using melatonin to help their child who has a trouble falling asleep. A medical professional should always evaluate insomnia or other sleeping disorders in children. Additionally, melatonin has been shown to protect against oxidative stress in various, highly divergent experimental systems. There are many reasons for its remarkable protective potential. In mammals, melatonin binds to a number of receptor subtypes including high-affinity (MT1 and MT2) and low-affinity (MT3, nuclear orphan receptors) binding sites, which are distributed throughout the central nervous system and periphery.

Barbital, the one of the series of barbiturates, has hypnotic, sedative, and anticonvulsant properties and used under the trade name Veronal. It calmed manic patients and helped melancholic patients to sleep and was an effective inducer of sleep in insomniacs, but at the same time compound could induced dependence. It was substituted by the butyl analog, butobarbital, which was three times stronger and its period of action was much shorter due to its lipophilicity. Barbital is a ligand of GABA-receptor complex and in addition, it could have another target, a creatine kinase.

Cinolazepam is a drug which is a benzodiazepine derivative. It possesses anxiolytic, anticonvulsant, sedative and skeletal muscle relaxant properties. Cinolazepam is not approved for sale in the United States or Canada. Cinolazepam binds to central benzodiazepine receptors, which interact allosterically with GABA receptors. This potentiates the effects of the inhibitory neurotransmitter GABA, increasing the inhibition of the ascending reticular activating system and blocking the cortical and limbic arousal that occurs following stimulation of the reticular pathways. Statistical analyses of objective sleep variables in men demonstrated a significant improvement of sleep maintenance after cinolazepam as reflected by an increase of sleep efficiency, decrease of wake time (during total sleep period) and number of awakenings as compared with the placebo. It is indicated for the treatment of sleep disorders of different etiologies.

Zopiclone (brand names Zimovane and Imovane) is a nonbenzodiazepine hypnotic agent used in the treatment of insomnia. The therapeutic pharmacological properties of zopiclone include hypnotic, anxiolytic, anticonvulsant, and myorelaxant properties. Zopiclone and benzodiazepines bind to different sites on GABAA-containing receptors, causing an enhancement of the actions of GABA to produce the therapeutic and adverse effects of zopiclone. The metabolite of zopiclone called desmethylzopiclone is also pharmacologically active, although it has predominately anxiolytic properties. One study found some slight selectivity for zopiclone on α1 and α5 subunits, although it is regarded as being unselective in its binding to α1, α2, α3, and α5 GABAA benzodiazepine receptor complexes. Desmethylzopiclone has been found to have partial agonist properties, unlike the parent drug zopiclone, which is a full agonist. The mechanism of action of zopiclone is similar to benzodiazepines, with similar effects on locomotor activity and on dopamine and serotonin turnover. A meta-analysis of randomised controlled clinical trials that compared benzodiazepines to zopiclone or other Z drugs such as zolpidem and zaleplon has found few clear and consistent differences between zopiclone and the benzodiazepines in sleep onset latency, total sleep duration, number of awakenings, quality of sleep, adverse events, tolerance, rebound insomnia, and daytime alertness. After oral administration, zopiclone is rapidly absorbed, with a bioavailability around 75–80%. Time to peak plasma concentration is 1–2 hours. High-fat meal preceding zopiclone administration does not change absorption (as measured by AUC), but reduces peak plasma levels and delays its occurrence, thus may delay the onset of therapeutic effects. The pharmacokinetics of zopiclone in humans are stereoselective. After oral administration of the racemic mixture, Cmax (time to maximum plasma concentration), area under the plasma time-concentration curve (AUC) and terminal elimination half-life values are higher for the dextrorotatory enantiomers, owing to the slower total clearance and smaller volume of distribution (corrected by the bioavailability), compared with the levorotatory enantiomer. In urine, the concentrations of the dextrorotatory enantiomers of the N-dimethyl and N-oxide metabolites are higher than those of the respective antipodes. Zopiclone is sometimes used as a method of suicide. It has a similar fatality index to that of benzodiazepine drugs, apart from temazepam, which is particularly toxic in overdose.

Nitrazepam (trade names: Alodorm, Apodorm, Arem, Mogadon, Nitrados, Nitrazadon, Nitrosun, Ormodon, Paxadorm, Remnos, and Somnite) is a hypnotic drug of the benzodiazepine class, indicated for the short-term relief of severe, disabling anxiety and insomnia. Nitrazepam has sedative and motor-impairing properties, as well as amnestic, anticonvulsant, and skeletal muscle relaxant effects. Nitrazepam is used to treat short-term sleeping problems (insomnia), namely difficulty falling asleep, frequent awakening, early awakening, or a combination of each. Nitrazepam is sometimes tried to treat epilepsy when other medications fail. It has been found to be more effective than clonazepam in the treatment of West syndrome, which is age-dependent epilepsy, affecting the very young. In uncontrolled studies, nitrazepam has shown effectiveness in infantile spasms and is sometimes considered when other anti-seizure drugs have failed. However, drowsiness, hypotonia, and most significantly tolerance to anti-seizure effects typically develop with long-term treatment, generally limiting Nitrazepam to acute seizure management. More common side effects may include: Central nervous system depression, including somnolence, dizziness, depressed mood, rage, violence, fatigue, ataxia, headache, vertigo, impairment of memory, impairment of motor functions, hangover feeling in the morning, slurred speech, decreased physical performance, numbed emotions, reduced alertness, muscle weakness, double vision, and inattention have been reported. Unpleasant dreams and rebound insomnia have also been reported. Nitrazepam is a long-acting benzodiazepine with an elimination half-life of 15–38 hours (mean elimination half-life 26 hours).

2-Dipiperonylaminoethanol is tertiary amine derivative classified by the WHO as an antipsychotic and anxiolytic drug. The compound was patented as antispasmodic medication in 1948.

WT-161 is a potent inhibitor of histone deacetylase (HDAC). It inhibits HDAC6, HDAC1, and HDAC2 with IC50 values of 0.4 nM, 8.35 nM, and 15.4 nM. The compound has demonstrated anti-tumor activity in preclinical models of multiple myeloma and breast cancer.

Ethallobarbital (Dormin, Dumex), an oral hypnotic drug that is included in the list of Schedule III drugs of the United States Controlled Substances Act.