A critical assessment of the melatonin effect on sleep in humans

Melatonin is synthesized and secreted during the dark period of the light-dark cycle. The rhythmic nocturnal melatonin secretion is directly generated by the circadian clock, located in mammals within the suprachiasmatic nucleus (SCN), and is entrained to a 24-hour period by the light-dark cycle. The periodic secretion of melatonin may be used as a circadian mediator to any system that can 'read' the message. In addition, direct effects of the hormone on the SCN could explain some of the melatonin effects on the circadian system. Duration of the melatonin nocturnal secretion is directly proportional to the length of the night and it has experimentally been demonstrated to be the critical parameter for photoperiod integration. The sites and mechanisms of action of melatonin for circadian and photoperiodic responses are far from being elucidated, but action through specific membrane receptor sites starts to emerge. A possible bicompartmental model of distribution for melatonin, the first compartment in plasma acting on peripheral organs and the second in the cerebrospinal fluid affecting neurally mediated functions at a much higher concentration, has recently been proposed. From earlier studies it was concluded that melatonin administration to humans reduces sleep latency and induces sleepiness and fatigue. More recently, the effect of lower pharmacologic or physiologic doses of melatonin was examined in different laboratories. These studies included young normal volunteers and patients with chronic insomnia, as well as dementia patients exhibiting sundowning syndrome. Irrespective of the method of assessment, melatonin showed effects in insomniac patients in most studies. With some exceptions, melatonin administration reduced sleep latency and/or increased total sleep time and sleep efficiency. Furthermore, melatonin was more effective when given to elderly insomniacs, or Alzheimer disease patients, although sleep improvement was not strictly correlated with prior levels of the hormone.

Sleep disturbance in generalized anxiety disorder and its treatment

Sleep laboratory and epidemiological studies indicate that insomnia is a frequent finding in patients with psychiatric disorders. In this respect, insomnia associated with a major depression or an anxiety disorder, mainly generalized anxiety disorder (GAD), is the most prevalent diagnosis. According to available evidence, the sleep disturbance associated with mild-to-moderate GAD is a sleep-maintenance insomnia, and to a lesser extent a sleep-onset insomnia. Insomnia associated with mild-to-moderate GAD generally responds to psychological treatments and anxiolytic benzodiazepines. Moreover, concomitant administration of hypnotic medication can be contemplated in patients with severe GAD.

Role of dorsal raphe nucleus serotonin 5-HT1A receptor in the regulation of REM sleep

Cholinergic neurons in the laterodorsal (LDT) and the pedunculopontine (PPT) tegmental nuclei act to promote REM sleep (REMS). The predominantly glutamatergic neurons of the REMS-induction region of the medial pontine reticular formation are in turn activated by cholinergic cells, which results in the occurrence of tonic and phasic components of REMS. All these neurons are inhibited by serotonergic (5-HT), noradrenergic, and presumably histaminergic (H2 receptor) and dopaminergic (D2 and D3 receptor) cells. 5-Hydroxytryptamine-containing neurons in the dorsal raphe nucleus (DRN) virtually cease firing when an animal starts REMS, consequently decreasing the release of 5-HT during this state. The activation of GABA(A) receptors is apparently responsible for this phenomenon. Systemic administration of the selective 5-HT1A receptor agonist 8-OHDPAT induces dose-dependent effects; i.e. low doses increase slow wave sleep and reduce waking, whereas large doses increase waking and reduce slow wave sleep and REM sleep. Direct injection of 8-OHDPAT or flesinoxan, another 5-HT1A agonist into the DRN, or microdialysis perfusion of 8-OHDPAT into the DRN significantly increases REMS. On the other hand, infusion of 8-OHDPAT into the LDT selectively inhibits REMS, as does direct administration into the DRN of the 5-HT1A receptor antagonists pindolol or WAY 100635. Thus, presently available evidence indicates that selective activation of the somatodendritic 5-HT1A receptor in the DRN induces an increase of REMS. On the other hand, activation of the postsynaptic 5-HT1A receptor at the level of the PPT/LDT nuclei decreases REMS occurrence.

Insônia primária: diagnóstico diferencial e tratamento

A insônia primária é uma dissonia caracterizada pela dificuldade em iniciar e/ou manter o sono e pela sensação de não ter um sono reparador durante um período não inferior a 1 mês. Do ponto de vista polissonográfico, é acompanhada de alterações na indução, na continuidade e na estrutura do sono. Geralmente aparece no adulto jovem, é mais freqüente na mulher e tem um desenvolvimento crônico. A insônia primária é observada de 12,5% a 22,2% dos pacientes portadores de insônia crônica, sendo precedida em freqüência somente na insônia de depressão maior. A insônia primária crônica deve se diferenciar da insônia vinculada a uma higiene inadequada do sono, uma síndrome depressiva ou um transtorno de ansiedade generalizado. O tratamento da insônia primária inclui: higiene adequada do sono, terapia cognitiva e de conduta e uso de fármacos hipnóticos. Entre esses últimos, se destacam o zolpidem e a zopiclona, que melhoram significativamente o sono sem alterar sua estrutura ou induzir a uma reincidência da insônia logo após uma interrupção brusca. Além disso, o desenvolvimento de fármaco-dependência e de vício é muito pouco freqüente.

Effect of SX-3228, a selective ligand for the BZ1 receptor, on sleep and waking during the light-dark cycle in the rat

The effects of the benzodiazepine1 (BZ1) receptor agonist SX-3228 were studied in rats (N = 12) implanted for chronic sleep procedures. Administration of 0.5, 1.0 and 2.5 mg/kg SX-3228, sc, to rats 1 h after the beginning of the light phase of the light-dark cycle induced a significant reduction of rapid-eye-movement sleep (REMS) during the third recording hour. Moreover, slow wave sleep (SWS) was increased during the fourth recording hour after the two largest doses of the compound. Administration of 0.5, 1.0 and 2.5 mg/kg SX-3228 one hour after the beginning of the dark period of the light-dark cycle caused a significant and maintained (6-h recording period) reduction of waking (W), whereas SWS and light sleep (LS) were increased. REMS values tended to increase during the entire recording period; however, the increase was statistically significant only for the 1.0 mg/kg dose during the first recording hour. In addition, a significant and dose-related increase of power density in the delta and the theta regions was found during nonREM sleep (LS and SWS) in the dark period. Our results indicate that SX-3228 is a potent hypnotic when given to the rat during the dark period of the light-dark cycle. Moreover, the sleep induced by SX-3228 during the dark phase closely resembles the physiological sleep of the rat.

Role of nitric oxide in sleep regulation: effects of L-NAME, an inhibitor of nitric oxide synthase, on sleep in rats

The effect of N(G)-nitro-L-arginine methyl ester (L-NAME), a competitive inhibitor of enzyme nitric oxide synthase (NOS), on spontaneous sleep during the light period, was studied in adult rats implanted for chronic sleep recordings. L-NAME was injected by subcutaneous (s.c.) or intracerebroventricular (i.c.v.) routes or was infused directly into the dorsal raphe nuclei (DRN). Subcutaneous (1.25-5.0 mg/kg) or i.c.v. (0.25-1.0 mg) administration of L-NAME increased waking (W) and reduced slow wave sleep (SWS) and rapid-eye-movement sleep (REMS) during the first 3 h of recording. On the other hand, direct application of L-NAME into the DRN (50.0-150.0 microg) induced an increment of W and a reduction of SWS without suppressing REMS. Values of W and SWS were significantly different compared with those of controls during the 6-h recording period. The effects of L-NAME observed after s.c. or i.c.v. administration confirm previous studies in rabbits and rats, in which the NOS inhibitor reduced sleep and increased W in a dose-dependent manner. It is possible that REMS suppression after L-NAME could be related to a reduction of acetylcholine release in areas critical for REMS promotion. A decrease in gamma-aminobutyric acid (GABA) release after nitric oxide synthesis inhibition could play a role in the reduction of SWS.

Polysomnographic study of the effect of melatonin on sleep in elderly patients with chronic primary insomnia

The effect of 3-mg melatonin capsules p.o. on sleep in ten elderly patients suffering from chronic primary insomnia was assessed by polysomnographic recordings. In general, melatonin significantly reduced wake time after sleep onset and increased total sleep time and sleep efficiency during the 2-week treatment period. In five of the ten patients treated with melatonin, the increase in total sleep time was clinically significant. Side effects were absent during the period of drug administration. A slight increase of power density in the delta and the theta regions was found during the early phase (i.e. nights 4-5) of melatonin administration, whereas the opposite changes were observed at a late phase of treatment (i.e. nights 15-16). No strict correlation was found between prior 6-sulphatoxymelatonin levels in urine and subsequent sleep improvement after receiving melatonin. Our results further support the proposal that melatonin is beneficial for sleep disturbances in elderly insomniacs.

Effects of accumbens m-chlorophenylbiguanide microinjections on sleep and waking in intact and 6-hydroxydopamine-treated rats

Effects of the 5-HT3 receptor agonist, m-chlorophenylbiguanide (10.0-40.0 microg), on sleep and waking were studied in control, vehicle-treated and 6-hydroxydopamine-injected rats. Bilateral injections of m-chlorophenylbiguanide into the nucleus accumbens of the control and the vehicle-infused animals significantly increased waking and reduced slow wave sleep. Rapid eye movement sleep (REM sleep) remained unchanged. Pretreatment with the selective 5-HT3 receptor antagonist, MDL 72222 (1aH,3a,5a, H-tropan-3-yl-3,5-dichloro-benzoate) (0.5 mg/kg, s.c.), reversed the effects of m-chlorophenylbiguanide (10.0-20.0 microg) on sleep and waking in the control group. Administration of the 5-HT3 receptor agonist to the 6-hydroxydopamine-treated animals modified only slightly the time spent in wakefulness and slow wave sleep, while REM sleep was significantly and dose dependently reduced. Our findings further support the proposal that increase of wakefulness and reduction of slow wave sleep after activation of 5-HT3 receptors, is partly related to the release of endogenous dopamine.

Effects of the D3 preferring dopamine agonist pramipexole on sleep and waking, locomotor activity and striatal dopamine release in rats

Quantitation of 2 h sessions after administration of the D3 preferring dopamine (DA) agonist pramipexole (10-500 microg/kg) showed dose-related effects on wakefulness (W), slow wave sleep (SWS) and REM sleep in rats. The 30 microg/kg dose of the DA agonist increased SWS and REM sleep and reduced W during the first recording hour, while the 500 microg/kg dose augmented W. On the other hand, W was increased while SWS and REMS were decreased after the 500 microg/kg dose during the second recording hour. The mixed D2- and D3 receptor antagonist YM-09151-2 (30-500 microg/kg), which per se affected sleep variables prevented the increase of REMS induced by pramipexole. Furthermore, the highest doses (500-1000 microg/kg) of the DA antagonist effectively antagonized the increase of W and reduction of SWS induced by the 500 microg/kg dose of the DA agonist. Pramipexole (30-100 microg/kg) induced a decrease of locomotor activity during the 2 h recording period. In addition, the 500 microg/kg dose gave rise to an initial reduction of motor behavior which was reverted 2 h later. Pramipexole (30 and 500 microg/kg) did not significantly affect striatal DA release during the first two hours following drug administration, as measured by microdialysis. It is tentatively suggested that D3 receptor could be involved in the pramipexole-induced increase of sleep and reduction of locomotor activity. On the other hand, the increase of W and of motor behavior after relatively high doses could be related to activation of postsynaptic D2 receptor.

Sleep in patients with chronic primary insomnia during long-term zolpidem administration and after its withdrawal

A double-blind trial was carried out to determine the effect of zolpidem or a placebo on sleep in two groups of insomniac patients with a diagnosis of moderate chronic primary insomnia. Zolpidem was given at a daily dose of 10 mg for 27 nights and was preceded (two nights) and followed (three nights) by a placebo. Zolpidem induced a significant increase of total sleep time, while total wake time and wake time after sleep onset were reduced. Values corresponding to stage 2 sleep were augmented, while stage 3 sleep and REM sleep showed no significant changes. Tolerance did not develop during the zolpidem administration period, and rebound insomnia did not show following abrupt interruption of drug administration. In addition, patients on zolpidem had a more peaceful sleep with no decrement of levels of alertness.

Sleep and waking during acute histamine H3 agonist BP 2.94 or H3 antagonist carboperamide (MR 16155) administration in rats

The present study evaluated the effects of histamine H3 receptor agonist BP 2.94 or H3 receptor antagonist carboperamide (MR 16155) given by oral route on sleep and waking in rats surgically prepared for long-term recordings. BP 2.94 produced a significant increase of slow-wave sleep (SWS) that was related to slight decreases of waking, light sleep, and REM sleep. Carboperamide significantly increased waking and decreased SWS and REM sleep. Pretreatment with carboperamide prevented the effect of BP 2.94 on SWS. It is suggested that the effects of BP 2.94 or carboperamide on sleep and waking could depend on changes in the availability of histamine at the postsynaptic H1 receptor. Alternatively, activation or blockade of the H3 heteroreceptors found in the central catecholamine, indolamine, and acetylcholine nerve endings could inhibit or increase the release of noradrenaline, serotonin, dopamine, and acetylcholine. This would secondarily result in changes of sleep variables.

Effects of selective activation of the 5-HT1B receptor with CP-94,253 on sleep and wakefulness in the rat

The effects of the 5-HT1B receptor agonist CP-94,253 were compared with those of the mixed beta-adrenoceptor and 5-HT1A/B receptor antagonist (+/-)pindolol in rats implanted for chronic sleep recordings. CP-94,253 (5.0-10.0 mg/kg) significantly increased waking and reduced slow wave sleep (SWS) and REM sleep (REMS). At 2.0-4.0 mg/kg (+/-)pindolol reduced REMS. Pretreatment with (+/-)pindolol (2.0-4.0 mg/kg) reversed the effect of CP-94,253 on waking and SWS, while REMS remained suppressed. It is suggested that the 5-HT1B receptor together with other 5-HT receptor subtypes may have a direct regulatory action on sleep and waking in the rat.

Single-dose ritanserin and alcohol in healthy volunteers: a placebo-controlled trial

A double blind cross-over design trial was carried out to investigate the effect of simultaneous administration of alcohol (0.5 g/kg) and ritanserin (10 mg) on biological and behavioral functioning. Twenty healthy volunteers were selected to participate in the study. To assess the effect of treatments the following evaluations were performed: psychomotor tests, vital signs, intoxication, euphoria, and mood. In addition, ritanserin and alcohol plasma concentration were measured. Psychomotor performance and vital signs during the ritanserin session did not differ significantly from the placebo session. Similar results were obtained in regard to alcohol intoxication, euphoria, and mood, except for tiredness and alertness, which were significantly different compared to placebo. Differences in blood alcohol concentration between the ritanserin and the placebo sessions did not attain significance. Plasma ritanserin concentration was 143 ng/ml 1 h after alcohol administration and decayed to 53 ng/ml 6 h after alcohol consumption in the active treatment session. Our findings tend to indicate that ritanserin neither enhances the central nervous system depressant effect of alcohol nor produces a pharmacokinetic interaction during acute alcohol ingestion.

Sleep and waking in 5,7-DHT-lesioned or (-)-pindolol-pretreated rats after administration of buspirone, ipsapirone, or gepirone

The effects of partial 5-HT1A receptor agonists buspirone (0.010-4.0 mg/kg), ipsapirone (0.010-6.0 mg/kg), and gepirone (0.025-4.0 mg/kg) on sleep and waking were studied in vehicle-treated and 5,7-dihydroxytryptamine (5,7-DHT)-injected rats. 5,7-DHT-treated animals showed a marked and significant serotonin and 5-HIAA depletion in the raphe regions of the pons and upper brain stem, cerebral cortex, hippocampus, and striatum. Subcutaneous administration of the partial agonists to both the vehicle-infused and the 5,7-DHT-treated animals significantly increased waking (W) and reduced light sleep (LS), slow-wave sleep (SWS), and REM sleep (REMS). Pretreatment with (-)pindolol (2.0 mg/kg) reversed the effects of buspirone and gepirone on W and non-REM sleep (LS + SWS) whereas REMS remained suppressed. (-)-Pindolol failed to reverse the effects of ipsapirone on sleep and W. The present results tend to indicate that increased W after acute administration of buspirone, ipsapirone, or gepirone depends upon the activation of postsynaptic 5-HT1A receptors. The well-known anxiolytic action observed after chronic administration of the azapirones seems to be related to mechanisms other that these involved in their stimulant effect.

Increased waking after intra-accumbens injection of m-chlorophenylbiguanide: prevention with serotonin or dopamine receptor antagonists

Bilateral injection of the selective 5-HT3 receptor agonist m-chlorophenylbiguanide (5.0-40.0 micrograms) into the nucleus accumbens of the rat significantly increased waking and decreased slow wave sleep. Rapid eye movement (REM) sleep remained unchanged. Pretreatment with the 5-HT3 receptor antagonist MDL 72222 (1aH,3a,5a, H-tropan-3-yl-3,5-dichloro-benzoate) (0.5 mg/kg s.c.) reversed the effects of m-chlorophenylbiguanide (10.0-20.0 micrograms) on sleep and waking. Blockade of the dopamine D1 or D2 receptor with (+)-SCH 23390 (0.25 mg/kg s.c.) or YM-09151-2 (cis-N-(1-benzyl-2-methylpyrrolidin-3-yl)-5-chloro-2-methoxy-4- methylaminobenzamide) (0.5 mg/kg s.c.), respectively antagonized the increase of waking and reduction of slow wave sleep induced by m-chloro-phenylbiguanide (10.0 micrograms). Our results tend to indicate that the increase of wakefulness after injection of the selective 5-HT3 receptor agonist m-chlorophenylbiguanide into the nucleus accumbens is partly related to the release of endogenous dopamine. In addition, they suggest that concomitant stimulation of both accumbens dopamine D1 and D2 receptor-related mechanisms is a necessary prerequisite to increase wakefulness.

The selective histamine H1-receptor agonist 2-(3-trifluoromethylphenyl)histamine increases waking in the rat

The effects of the selective histamine H1-receptor agonist, 2-(3-trifluoromethylphenyl)histamine, were studied in rats implanted with electrodes for chronic sleep recordings. 2-(3-Trifluoromethylphenyl)histamine (80-120 micrograms) injected into the left lateral ventricle increased wakefulness, whereas slow wave sleep was reduced. Pretreatment with pyrilamine (2.0 mg/kg) prevented the effects of the H1-receptor agonist on wakefulness and slow wave sleep. Our results further support the involvement of histamine in the modulation of the waking state.

Zolpidem and rebound insomnia--a double-blind, controlled polysomnographic study in chronic insomniac patients

In a parallel-group, placebo-controlled, polysomnographic study with randomization, the possible occurrence of rebound insomnia was evaluated in 24 patients suffering from moderate to severe chronic insomnia and receiving either triazolam 0.5 mg, zolpidem 10 mg, or placebo. Treatment duration was 27 nights, followed by three placebo-controlled withdrawal nights. Both drugs showed significant efficacy compared to placebo during the active treatment period. A trend toward tolerance was noted in the triazolam group but not in the zolpidem one. The increase in total sleep time in the zolpidem group was accompanied by an increase in the number of sleep cycles. When active treatment was discontinued, clear rebound insomnia was present in the triazolam group while it was not possible to observe any rebound in the placebo and zolpidem groups. Subjective feelings of the patients, which were assessed by means of visual analog scales, correlated well with polysomnographic data. Our findings tend to indicate that, even after long-term treatment, zolpidem does not induce rebound insomnia or daytime anxiety.

Depletion of brain serotonin by 5,7-DHT: effects on the 8-OH-DPAT-induced changes of sleep and waking in the rat

The effect of 5-HT1A receptor agonist 8-OH-DPAT on sleep and wakefulness was studied in rats with selective serotonin depletion after ICV administration of the neurotoxin 5,7-dihydroxytryptamine (5,7-DHT). Injection of 8-OH-DPAT to vehicle-treated animals induced biphasic effects, such that low doses (0.010 mg/kg) which act perferentially on the somatodendritic autoreceptor decreased wakefulness (W) and increased slow wave sleep (SWS), while higher doses (0.375 mg/kg) which stimulate postsynaptic receptors caused opposite effects. REM sleep was suppressed irrespective of the dosage given. Injection of the 0.010 mg/kg dose in the 5,7-DHT-treated rats did not result in significant changes in sleep or W. On the other hand, the 0.375 mg/kg dose produced changes in sleep variables which were similar to those described in the vehicle-treated animals. Our findings tend to indicate that increased SWS after low doses of 8-OH-DPAT depends upon the activation of inhibitory somatodendritic 5-HT1A receptors, while increased W after higher doses of the compound is related to stimulation of postsynaptic receptors.

Stereoselective antagonism by the pindolol enantiomers of 8-OH-DPAT-induced changes of sleep and wakefulness

The effects of 5-HT1A receptor agonist 8-OH-DPAT were compared with those of the mixed beta-adrenoceptor and 5-HT1A receptor antagonist (-)pindolol, and the selective beta-adrenoceptor antagonist betaxolol in rats implanted for chronic sleep recordings, 8-OH-DPAT (0.375 mg/kg) significantly increased wakefulness and decreased slow wave sleep (SWS) and REM sleep (REMS). At 2.0-4.0 mg/kg (-)pindolol reduced REMS. Betaxolol in doses of 1.0 and 2.0 mg/kg did not significantly modify sleep variables. Pretreatment with (-)pindolol (2.0-4.0 mg/kg) reversed the effect of 8-OH-DPAT on waking and SWS, while (+)pindolol (4.0 mg/kg) and betaxolol (2.0 mg/kg) were ineffective in this respect. The stereoselective antagonism by the pindolol enantiomers supports the proposal that 8-OH-DPAT-induced increase of waking and decrease of SWS depends on the activation of 5-HT1A receptors. The absence of antagonism by betaxolol tends to indicate that prevention by (-)pindolol of waking increase did not involve beta-adrenoceptors.

The effects of selective activation of the 5-HT3 receptor with m-chlorophenylbiguanide on sleep and wakefulness in the rat

The effects of the 5-HT3 receptor agonist, m-chlorophenylbiguanide, were compared with those of the 5-HT3 receptor antagonist, MDL 72222, in rats implanted with electrodes for chronic sleep recordings. m-Chlorophenylbiguanide (12.5-50.0 micrograms) injected into the left lateral ventricle increased wakefulness and rapid eye movement (REM) sleep latency, whereas slow wave sleep, REM sleep and the number of REM periods were reduced. MDL 72222 (0.1-1.0 mg/kg, s.c.) induced a delayed and dose-dependent increase of slow wave sleep. Pretreatment with MDL 72222 (0.1-0.5 mg/kg) prevented the effects of m-chlorophenylbiguanide (50 micrograms) on wakefulness and sleep. It is suggested that the increase of wakefulness after 5-HT3 receptor activation could be related to the release of endogenous serotonin and dopamine.

The effects of ritanserin on mood and sleep in abstinent alcoholic patients

A trial was carried out to determine the effect of ritanserin or a placebo on sleep and mood in two groups of abstinent alcoholic patients. Their condition was characterized by both alcohol dependence and dysthymia, associated with a personality disorder. They were included in the study after 30 days of sobriety. Ritanserin was given at a daily dose of 10 mg for 28 days and was preceded (10 days) and followed (2 days) by a placebo. Plasma ritanserin concentration after administration of the 28th dose was higher than after the first dose. Peak levels of ritanserin from the first to the 28th dose increased approximately three-fold. In the ritanserin group there was a reduction of total waking time. Total sleep time increase was associated with significantly larger amounts of nonrapid eye movement sleep. Slow wave sleep and rapid eye movement sleep (in minutes or as a percent of total sleep time) were not significantly modified. Patients on ritanserin achieved a progressive improvement of their dysthymia. As compared to the placebo group, a statistically significant decrease of the Hamilton Rating Scale for Depression and Hamilton Rating Scale for Anxiety was found in the ritanserin group after 1 week of treatment. The absence of an effect in the placebo-treated group suggests that the clinical response and sleep improvement were mainly related to ritanserin administration.

The effect of midazolam on transient insomnia

We have assessed the effect of midazolam on sleep in a model of transient insomnia in healthy adults using polysomnographic recordings. The subjects were randomly assigned to one of three treatment groups (placebo or midazolam 7.5 or 15 mg) and spent a single night in the sleep laboratory. Midazolam or placebo were given double-blind immediately before turning off the lights. Midazolam 15 mg was effective in inducing sleep, while 7.5 mg and 15 mg produced improvement in the maintenance of sleep. Subjectively, sleep latency and the number of awakenings were reduced dose-dependently. Midazolam did not impair psychomotor performance on the morning after administration.

Involvement of histamine in the control of the waking state

Available evidence indicates that histamine (HA) plays a neuroregulatory role in the waking state. Support for this proposal is provided by electrophysiological, lesion and pharmacological studies, as well as by fluctuations of HA levels according to a circadian pattern. Thus, 1) HA-containing neurons unit activity changes dramatically as a function of behavioral state across the sleep-wakefulness continuum, from 2.3 spikes/sec during active waking to virtual silence during slow wave sleep and REM sleep; 2) HA levels reach a minimum during the dark phase followed by an increase during the light period in rats kept under controlled environmental conditions; in addition histidine decarboxylase and HA-N-methyl-transferase activities are higher during darkness; 3) lesions or cooling of the posterior hypothalamus in the area where HA-immunoreactive neurons are located gives rise to a state of somnolence or hypersomnia; 4) 2-thiazolylethylamine, the predominantly H1-receptor agonist and thioperamide, the H3-receptor antagonist increase wakefulness in laboratory animals, while the HA synthesis inhibitor a-fluoromethylhistidine, the H1-receptor antagonists mepyramine, diphenhydramine and chlorpheniramine, and the H3-receptor agonist (R)-a-Me-histamine produce opposite effects.

Dose-dependent effects of the 5-HT1A receptor agonist 8-OH-DPAT on sleep and wakefulness in the rat

Sleep and wakefulness were studied in rats following administration of a selective 5-HT1A agonist (8-OH-DPAT), a non-selective 5-HT1A antagonist [(-) pindolol] and a combination of 8-OH-DPAT and (-) pindolol. 8-OH-DPAT (1.0-4.0 µg) injected into the dorsal raphe nucleus increased slow-wave sleep and decreased wakefulness. Administration of the 5-HT1A agonist by subcutaneous route induced biphasic effects such that low doses (0.010 mg kg-1) decreased wakefulness and increased slow-wave sleep while higher doses (0.375 mg kg-1) induced opposite effects. REM sleep was suppressed and REM latency was increased, what could be tentatively ascribed to a non-specific effect (hypothermia). (-) Pindolol (1.0-4.0 mg kg-1) induced an initial increase of wakefulness and a decrease of NREM sleep and REM sleep. Thereafter, NREM sleep showed a marked increase while REM sleep remained depressed. Pretreatment with (-) pindolol reversed the effects of both small and large doses of 8-OH-DPAT on slow-wave sleep and wakefulness. The opposite effects, observed on the waking EEG after activation of either serotonin autoreceptors or postsynaptic 5-HT1A receptors with adequate doses of 8-OH-DPAT, tend to indicate an active role for the 5-HT1A receptor in the control of the waking state.

Effects of selective activation or blockade of the histamine H3 receptor on sleep and wakefulness

The effects of the histamine H3 receptor agonist, (R)-alpha-methylhistamine were compared with those of the histamine H3 antagonist, thioperamide, in rats implanted with electrodes for chronic sleep recordings. (R)-alpha-Methylhistamine (1.0-4.0 micrograms) injected bilaterally into the premammillary area where histamine immunoreactive neurons have been detected increased slow wave sleep, whereas wakefulness and REM sleep were decreased. No significant effects were observed when (R)-alpha-methylhistamine (1.0-8.0 mg/kg) was administered i.p. Thioperamide (1.0-4.0 mg/kg i.p.) increased wakefulness and decreased slow wave sleep and REM sleep. Pretreatment with thioperamide (4.0 mg/kg) prevented the effects of (R)-alpha-methylhistamine (2.0 micrograms) on slow wave sleep and wakefulness. Our results further support an active role for histamine in the control of the waking state.

The effects of moclobemide on nocturnal sleep of depressed patients

The effect of moclobemide, a short-acting, reversible, preferential type-A MAO inhibitor (300 mg daily in three divided doses), on the sleep of eight depressed patients was assessed by polysomnographic recordings in a 4-week therapeutic trial. Six patients showed an improvement greater than 50% on the Hamilton Depression Rating Scale. Compared to placebo, patients receiving moclobemide showed improved sleep continuity as judged by the decrease in wake time after sleep onset and total wake time, particularly during the intermediate and late stages of drug administration. Total sleep time increase was comprised of larger amounts of stage 2 NREM sleep. REM sleep latency was significantly increased and REM sleep % decreased during the drug administration period. However, in contrast to the older, non-selective and selective MAOIs, moclobemide had a mild REM sleep suppressant effect.

Sleep variables are unaltered by zolantidine in rats: are histamine H2-receptors not involved in sleep regulation?

The effects of the H1-receptor antagonist diphenhydramine and the brain-penetrating H2-receptor antagonist zolantidine were studied in rats implanted for chronic sleep recordings. Diphenhydramine (1.0-4.0 mg/kg) significantly increased slow wave sleep and decreased wakefulness. Zolantidine (0.25-8.0 mg/kg) had no significant effects on any of the sleep parameters examined. One possibility is that zolantidine did not enter the brain in sufficient concentration to produce significant changes on sleep and wakefulness. Another possibility is that blockade of H2-receptor involved parts of the brain other than those implicated in the sleep-wake cycle. The feasibility remains that H2-receptors are not involved in sleep regulation. The absence of selective, brain-penetrating H2-receptor agonists precludes a more detailed analysis of the role of this subtype of receptor in the control of sleep and wakefulness.

Sleep during acute dopamine D1 agonist SKF 38393 or D1 antagonist SCH 23390 administration in rats

The effect of the D1 dopamine (DA) receptor agonist SKF 38393 was compared with that produced by the D1-receptor antagonist, SCH 23390, in rats implanted with electrodes for chronic sleep recordings. SKF 38393 (0.1 to 4.0 mg/kg) significantly suppressed rapid-eye-movement sleep (REMS) after the highest dose. SCH 23390 (0.1 to 2.0 mg/kg) increased slow-wave sleep (SWS), whereas wakefulness (W) and REMS were decreased. Pretreatment with SKF 38393 (0.5 mg/kg) prevented the effects of SCH 23390 (0.25 mg/kg) on W and SWS. However, REM sleep showed a further depression. Pretreatment with SKF 38393 (2.0 mg/kg) or SCH 23390 (0.25 mg/kg) failed to modify the increase of SWS and decrease of W induced by D2 receptor agonist bromocriptine (0.5 mg/kg) in a dose that selectively stimulates DA autoreceptors. On the other hand, SCH 23390 (0.25 mg/kg) failed to prevent REMS depression induced by bromocriptine (6.0 mg/kg) in a dose that preferentially acts at postsynaptic sites. Pretreatment with SCH 23390 (0.25 mg/kg) prevented the increase of W and decrease of SWS induced by the 5-HT2 receptor agonist DOI (0.25 mg/kg). Given the "fragility" of REMS in the rat, nonspecific factors could be contributing to its depression after SKF 38389 or SCH 23390 administration. Inhibition of D1 receptors could be responsible for SCH 23390-induced increase of SWS and decrease of W. However, a blockade of 5-HT2 receptors could be partly involved in these effects. Neither SKF 38393 nor SCH 23390 exerted activity on the sleep-wake cycle, which could be considered to reflect effects at DA autoreceptors.

Combined effects of midazolam and ethanol on sleep and on psychomotor performance in normal subjects

A study was carried out on the effects of midazolam 15 mg in conjunction with ethanol 0.5 g/kg on objective and subjective sleep parameters and psychomotor performance in normal subjects. Midazolam significantly decreased total wake time. Total sleep time (TST) increase was related to larger amounts of stage 2 NREM sleep. Ethanol showed similar effects on sleep, although TST increase was associated with nonsignificant increments of NREM sleep and REM sleep. Ethanol slightly potentiated midazolam effects on sleep. Accordingly, total wake time, REM sleep time and number of wakes showed further depression than with midazolam alone. Subjective evaluations showed relatively good correlation with sleep laboratory findings. In addition, the different treatments did not impair subject's psychomotor performance the morning after their administration.

Effects of the selective dopamine D-2 receptor agonist, quinpirole on sleep and wakefulness in the rat

The effects of the dopamine D-2 receptor agonist, quinpirole, were compared with those produced by dopamine D-2 antagonist, YM-09151-2, in rats implanted with electrodes for chronic sleep recordings. Quinpirole (0.015-1.0 mg/kg) induced biphasic effects such that low doses decreased wakefulness and increased sleep, while higher doses induced the opposite effects. At 0.015 mg/kg, YM-09151-2 slightly augmented wakefulness, while at 1.0-2.0 mg/kg it significantly increased light sleep but depressed REM sleep. Pretreatment with YM-09151-2 in a dose which preferentially acts at presynaptic sites reversed the suppressant effects of a low dose of quinpirole on wakefulness and slow wave sleep. In contrast, the administration of YM-09151-2 in a dose which blocks postsynaptic D-2 receptors prevented the effect of a high dose of quinpirole on wakefulness and slow wave sleep; the depression of REM sleep was not affected. The opposite effects observed on the waking EEG after activation of either dopamine autoreceptors or postsynaptic D-2 receptors with adequate doses of quinpirole tend to indicate an active role for DA in the control of the waking state.

Effect of a reversible monoamine oxidase-A inhibitor (moclobemide) on sleep of depressed patients

The effect of moclobemide, a short-acting, reversible, preferential monoamine oxidase-A inhibitor in a 4-week therapeutic trial, on the sleep of ten depressed patients, was assessed by polysomnographic recordings. Compared with their time on placebo, patients receiving moclobemide showed improved sleep continuity, particularly during the intermediate and late stages of drug administration. The total increase in sleep time was comprised of larger amounts of stage 2 non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. Withdrawal of moclobemide was followed by a further increase of REM sleep, although values did not surpass those sometimes observed in adults with normal sleep. In these patients, the symptoms of depression were rated as being significantly improved during the study period.

Sleep and nighttime pruritus in children with atopic dermatitis

The number of scratching episodes and average frequency with which they started during each sleep stage as well as the effects of nighttime pruritus on objective sleep parameters in nine children with atopic dermatitis were assessed in the sleep laboratory. Scratching episodes occurred during rapid eye movement (REM) sleep and non-REM (NREM) sleep. The largest average frequency corresponded to stage 1, followed by stage 2, REM sleep, stage 4, and stage 3. Sleep maintenance was markedly altered. Total sleep time decrease was related mainly to smaller amounts of stage 4 NREM sleep. REM sleep percentage of total sleep time was increased as compared with normal children of the same age. Furthermore, in six of nine patients REM sleep latency was found to be decreased.

Effect of zolpidem on sleep in insomniac patients

The effect of zolpidem 10 mg p.o. on sleep in patients with persistent psychophysiological insomnia was assessed by polysomnographic recordings. An improvement in sleep with no rebound insomnia was observed during treatment for two weeks. Time awake after the onset of sleep was reduced after one week and increased after two weeks, whereas sleep latency remained reduced. Zolpidem markedly increased the duration of Stage 2 sleep without affecting either slow wave sleep or REM sleep. Subjective evaluation of improvement in sleep was well correlated with sleep laboratory findings. Zolpidem did not impair the immediate memory or psychomotor performance of patients on the morning after its administration. Side-effects during the period of drug administration included drowsiness, fatigue, headache, anxiety and irritability. They were mild or moderate and wore off soon after awakening.

Effect of DSP-4, a noradrenergic neurotoxin, on sleep and wakefulness and sensitivity to drugs acting on adrenergic receptors in the rat

DSP-4, a neurotoxin which produces a marked and long-lasting depletion of norepinephrine (NE) in the central nervous system, was given in a dose of 50 mg/kg by i.p. route to rats prepared for chronic sleep recordings. Light sleep was significantly increased and REM sleep decreased during the first 2 days following DSP-4. Thereafter, REM sleep showed a consistent increase which attained significance on days 5 and 6 postinjection, thus indicating a permissive role for NE on this behavioral state. We examined also whether pretreatment with DSP-4 would modify the effects of clonidine, yohimbine, methoxamine, or clenbuterol on sleep and wakefulness. The sensitivity to alpha 2-agents, methoxamine, and clenbuterol was respectively slightly increased or unchanged, decreased, and clearly increased after DSP-4.

Effects of a-fluoromethylhistidine on sleep and wakefulness in the rat. Short note

The histamine synthesis inhibitor a-fluoromethylhistidine (a-FMH, 50 mg/kg, i.p.) significantly reduced wakefulness (W) and light sleep and increased slow wave sleep (SWS) and REM sleep during the light period in rats housed under 12 h light/12 h dark conditions (12L/12D). When animals were housed under 16 h light/8 h dark (16L/8D) they remained awake for a longer period of time during the dark as compared to the 12L/12D lighting cycle. Under this condition a-FMH 50 mg/kg significantly decreased W and increased SWS. Our results tend to indicate that histamine intervenes in sleep-wakefulness regulation. In addition, histamine could be partly involved in the abnormally increased incidence of W observed during the dark in rats housed under 16L/8D conditions.

Biphasic effects of dopamine D-2 receptor agonists on sleep and wakefulness in the rat

The effects of the dopamine (DA) receptor agonists apomorphine, bromocriptine and pergolide were compared with those produced by a DA receptor antagonist, haloperidol, in rats implanted with electrodes for chronic sleep recordings. Apomorphine (0.025-2.0 mg/kg) and bromocriptine (0.25-6.0 mg/kg) induced biphasic effects such that low doses decreased wakefulness (W) and increased slow wave sleep (SWS) and REM sleep (REMS), while large doses induced opposite effects. The effects of pergolide (0.05-0.5 mg/kg) on W and SWS were also biphasic, while REMS was suppressed over the range of dosages given. At 0.040 mg/kg, haloperidol increased W, while at 0.160 mg/kg it produced the opposite effect. Pretreatment with haloperidol (0.020 mg/kg) in a dose which preferentially acts at presynaptic sites reversed the effects of low doses of apomorphine, bromocriptine or pergolide on sleep and W. However, the compound differed substantially in its ability to block agonist effects. The increase in sleep after low doses of apomorphine, bromocriptine or pergolide could be related to activation of presynaptic D-2 receptors located on DA axons of mesolimbic and mesocortical systems. In addition, inhibition of norepinephrine and acetylcholine neurons having inhibitory D-2 receptors could contribute to the increase of sleep after small doses of the DA agonists.

Disturbances of sleep and wakefulness associated with the use of antihypertensive agents

Sleep disturbances are frequently associated with the use of antihypertensive drugs. They are observed mainly during the administration of drugs that affect central adrenergic mechanisms. Beta-adrenoceptor antagonists which readily penetrate into the brain (propranolol, pindolol) increase wakefulness and/or decrease REM sleep. Alpha 2-adrenoceptor agonists (clonidine, guanfacine) markedly reduce the duration of REM sleep. The catecholamine depleting agent reserpine increases REM sleep during single or repeated-dose administration, while the MAOI phenelzine shows opposite effects. The 5-HT2 antagonist ritanserin, which is chemically related to the antihypertensive agent ketanserin, increases slow wave sleep while REM sleep is decreased. Sleep disturbances have not been reported during the administration of calcium entry antagonists. However, they seem to modify the effects of hypnotics and CNS stimulants. There are no formal studies on the effects of angiotensin converting enzyme inhibitors and vasodilators on sleep in man.

Short-term sleep laboratory evaluation of midazolam in chronic insomniacs. Preliminary results

The effects of 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5-a] [1,4]benzodiazepine (midazolam, Ro 21-3981, Dormicum) in oral formulation of 15 and 30 mg on the sleep cycle of patients suffering from insomnia were assessed by means of polysomnographic recordings using a double-blind cross-over design. Both doses of midazolam were effective in improving sleep on short-term administration. In addition, significantly larger decrements of non-REM (NREM) sleep latency and of wake time through the 3rd third of night and nonsignificant trends toward smaller number of awakenings as well as shorter total wake time and longer NREM sleep time were induced by the 30 mg dose. Irrespective of the dosage sleep was almost exclusively increased at the expense of NREM sleep. Following 3 days treatment there was no rebound insomnia. These preliminary results suggest that the 15 mg dose could be appropriate in patients with difficulties in falling asleep, while the 30 mg dose would be more appropriate for patients who also experience difficulties in staying asleep.

Effects of H1- and H2-histamine receptor agonists and antagonists on sleep and wakefulness in the rat

The H1-receptor agonist 2-thiazolylethylamine (2-TEA) given by i.c.v. route dose-dependently increased wakefulness (W) and decreased NREM sleep (NREMS) and REM sleep (REMS) in rats prepared for chronic sleep recordings. The H1-receptor antagonists pyrilamine and diphenhydramine given by i.p. route decreased W and increased NREMS. Pyrilamine prevented the increase of W and decrease of NREMS produced by 2-TEA. However, REMS reduction was not antagonized, what tends to suggest that two different mechanisms could be involved in the 2-TEA-induced effects on NREMS and REMS. Cimetidine which blocks H2-receptors, when given by i.p. route showed no significant effects on sleep and W. Administration of the H2-receptor agonist dimaprit and the H2-receptor antagonists cimetidine, metiamide and ranitidine by i.c.v. route induced the appearance of high voltage spikes at cortical leads, thus leaving inconclusive the matter of their effects on sleep and wakefulness. Our results tend to support the proposal that the H1-receptor intervenes in sleep-wakefulness regulation. Limitations in the available H2-receptor agonists and antagonists presently preclude a more detailed analysis of the role of H2-receptors on sleep and W.

Spontaneous cerebellar nuclei PGO-like waves in natural paradoxical sleep and under reserpine

PGO-like spikes were described in chronically implanted cats at the cerebellar nuclei, dentatus, fastigii and interpositus, bipolarly and monopolarly recorded during natural paradoxical sleep. They showed close similarities with known PGO at occipital cortex and lateral geniculate nucleus: wave form, duration and amplitude were coincident. Moreover fast activity frequency increment in the last part of slow wave sleep also was observed at cerebellar loci. The peak-to-peak latency measurements demonstrated that the occipital cortex PGO lagged the nucleus dentatus PGO-like waves in 20-22 msec. The phasic cerebellar waves were not always related to eye movements. Acute experiments with a previous low dose of reserpine showed the PGO-like spikes when an exploring electrode penetrated a cerebellar nucleus. Chronically implanted cats, treated with reserpine, showed the phasic cerebellar waves during wakefulness and, after a few days, during the recovered paradoxical sleep. Based on electrophysiology and the reserpine experiments a common pontine generating mechanism for PGO and cerebellar PGO-like activity is proposed. It is also hypothesized that the cerebellum could participate in sleep physiology mainly related to phasic events without excluding a tonic function.

Effects of methoxamine and alpha-adrenoceptor antagonists, prazosin and yohimbine, on the sleep-wake cycle of the rat

A study was carried out on the effects of methoxamine, prazosin, and yohimbine on the sleep-wake cycle in rats prepared for chronic sleep recordings. Methoxamine (4-8 mg/kg), an alpha 1-adrenoceptor agonist, induced a dose-related increase in wakefulness (W) and a decrease in slow-wave sleep (SWS) and REM sleep (REMS). Prazosin (0.125-1 mg/kg), which selectively blocks alpha 1-adrenoceptors, modified only slightly the amount of time spent in W and SWS, and consistently decreased REMS values. Prazosin (0.5 mg/kg) reversed the effects of methoxamine, decreasing W and increasing sleep. Yohimbine (3 mg/kg), which blocks alpha 2-adrenoceptors, augmented W and diminished sleep. Methoxamine (4 mg/kg) in animals pretreated with yohimbine (3 mg/kg) induced a further decrease of SWS and REMS and an increase of W. Thus, pharmacological activation of alpha 1- or blocking of alpha 2-adrenoceptors appears to decrease sleep and increase W. Further, blocking of alpha 1-adrenoceptors decreases REMS. Rapid eye movement sleep depression by the alpha 1-agonist or the alpha 1-antagonist is tentatively ascribed to a critical change in noradrenergic transmission in the brain.

Effect of xipamide and furosemide on guinea pig cochlear recorded potentials

The effects of furosemide and xipamide on guinea pig cochlear potentials were studied under acute conditions. Auditory nerve action potentials (AP) and cochlear microphonics (CM) were depressed by both diuretics in a dose-related manner. Furosemide was more effective on AP than on CM. In contrast, the xipamide-induced reductions of AP and CM were similar. Our results suggest that the depressive effects of furosemide or xipamide may be related to a direct action on cochlear mechanisms.

Midazolam and sleep in insomniac patients

The effects of midazolam (15 and 30 mg p.o.) on the sleep of insomniac patients were assessed by means of polysomnographic recordings. As compared with placebo, 15 mg midazolam significantly increased non-REM sleep while other objective measures of insomnia were only slightly modified. At the 30 mg dose, midazolam significantly decreased total wake time and wake time after sleep onset. On the other hand, total sleep and non-REM sleep time were increased. No development of tolerance was observed following 2 weeks of drug use.

Catecholamines and the sleep-wake cycle. I. EEG and behavioral arousal

The exact role of catecholamines (CA) on the sleep-wake cycle is still controversial. Critical analysis of lesion studies tends to suggest a neuromodulatory role for both dopamine (DA) and norepinephrine (NE) on EEG and behavioral arousal. Support for this view is provided by pharmacological studies in which catecholaminergic systems are activated or inhibited. Taken together they show that disturbances in the dynamic balance between neurochemical systems may alter the conditions for wake-triggering mechanisms to express at optimal levels. Large electrolytic or neurotoxic lesions which affect noradrenergic and dopaminergic structures are associated with marked and prolonged EEG changes and decreased behavioral arousal, respectively. In contrast, specific and circumscribed damage restricted to these systems is followed by a transient decrease in waking activity. Thus, results observed after large central lesions are most probably related to destruction of non-catecholaminergic neurons. Inhibition of brain CA synthesis causes behavioral sedation and a decrease in waking activity. Selective pharmacological stimulation of presynaptic alpha-adrenergic (alpha 2) receptors tends to decrease waking, while opposite effects result from alpha 2-receptor blockade. Drugs with agonistic activity at postsynaptic alpha-adrenergic (alpha 1) sites increase EEG desynchronization, but specific blockade of alpha 1-receptor does not result in marked decreases of waking EEG. In contrast, treatments which simultaneously block NE and DA receptors significantly affect waking. Beta-adrenergic receptor blockers show no conclusive effects on waking or sleep. Selective DA-receptor agonists induce biphasic effects, with low doses decreasing and large doses increasing cortical desynchronization and motility. Opposite effects are observed in laboratory animals after injection of specific DA-receptor blockers.

Sleep laboratory study of the effects of midazolam in insomniac patients

The effects of midazolam, a short-acting imidazobenzodiazepine, on the sleep cycle of insomniac patients were assessed by means of polygraphic recordings. Baseline placebo nights were compared with drug (30 mg p.o.) and placebo withdrawal nights. The compound was effective in inducing and maintaining sleep on short- and intermediate-term administration. Tolerance was not observed following two weeks of drug use. Subjective reports corroborated the effectiveness of midazolam as a hypnotic. In regard to its effects on sleep stages, midazolam markedly decreased Stage 3 and abolished Stage 4 sleep, while Stage 2 was augmented. REM sleep percentage was not significantly affected. Withdrawal of midazolam was followed by rebound insomnia, in which sleep latency, total wake time and wake time after sleep onset were increased above baseline. Side-effects related to midazolam administration included headache, muscular weakness and dizziness. They were mild and wore off 1-2 hours after awakening.

Effects of oxolinic acid on the sleep-wakefulness cycle of the rat

1 A study was carried out in rats (prepared for chronic sleep recording) of the effects of oxolinic acid on the sleep-wakefulness cycle.2 In addition, the actions of oxolinic acid on the sleep-wake cycle were assessed after pretreatment with drugs interfering with central catecholamine mechanisms or facilitating central gamma-aminobutyric acid (GABA) activity.3 Oxolinic acid (8-32 mg/kg) induced a significant and dose-related increase of waking EEG, while slow wave and REM sleep were decreased.4 The effects of oxolinic acid on waking, slow wave and REM sleep were antagonized by alpha-methyl-p-tyrosine (50-100 mg/kg) which interferes with the synthesis of catecholamines.5 FLA-63 (25 mg/kg) which is a specific inhibitor of noradrenaline synthesis, was effective in blocking oxolinic acid-related increase of waking and decrease of slow wave sleep.6 Haloperidol (0.4-0.6 mg/kg) which blocks central dopamine and noradrenaline receptors, reversed oxolinic acid-induced actions on waking and slow wave sleep. Spiroperidol (2-4 mg/kg) which interferes with dopamine and 5-hydroxytryptamine mechanisms, only antagonized the effect of oxolinic acid on light slow wave sleep. REM sleep was further decreased by both neuroleptic agents.7 gamma-Hydroxybutyrate (25-50 mg/kg), which acts as a GABA agonist and amino-oxyacetic acid (20 mg/kg), which considerably increases central GABA levels, were ineffective in blocking oxolinic acid-related disruption of the sleep-wake cycle.8 Our results suggest that the catecholamines are involved in the arousing effect of oxolinic acid.

Sleep laboratory and clinical studies of the effects of triazolam, flunitrazepam and flurazepam in insomniac patients

Polysomnographic recordings allow the recognition of three normal sleep stages: wakefulness, NREM and REM sleep. There are quantitative changes in these stages from childhood to old age. Most characteristic are progressive decreases in total sleep time, stage 4 NREM sleep and REM sleep. Insomnia can be defined as an alteration of both the quantity and quality of sleep. It can be associated with psychophysiological factors, psychiatric disorders, use of drugs and alcohol, sleep apnea, sleep-related myoclonus and restless legs, medical, toxic and environmental conditions, or REM sleep interruptions. At present, the benzodiazepines are the most frequently prescribed hypnotics. Their efficacy has been evaluated in the sleep laboratory and by means of sleep questionnaires (clinical studies). Their derivatives are grouped according to their pharmacokinetic profiles as short acting (triazolam), intermediate acting (flunitrazepam) and long acting (flurazepam). At the EEG level these compounds induce an increase in fast frequencies and in the number of sleep spindles. Slow wave activity is markedly decreased. All of the derivatives effectively and significantly induce and maintain sleep. Total sleep time increase is related to an imcrement of stage 2 sleep while REM sleep and stages 3 + 4 sleep are consistently reduced. Triazolam withdrawal is followed by a rebound insomnia. In contrast, under the same circumstances, flurazepam has a carry-over effect.