Antipsychotic-induced somnolence should be managed with sleep hygiene education, selecting an antipsychotic with a lower risk of somnolence, and initiating at a lower dose with a slower titration based on psychiatric diagnoses, a review published in CNS Drugs reports.

Study authors evaluated the incidence of somnolence through a MEDLINE search for randomized, double-blind, placebo- or active-controlled studies of adults treated with antipsychotics for schizophrenia, mania, bipolar depression, or bipolar disorder. They estimated the absolute risk increase (ARI) and the number needed to harm (NNH) of an antipsychotic agent vs. placebo or an active comparator for the same psychiatric disorder. 

Based on the ARI for acute schizophrenia, bipolar mania, and bipolar depression, antipsychotics were categorized as high somnolence (eg, clozapine), moderate somnolence (eg, olanzapine, perphenazine, quetiapine, risperidone, ziprasidone), and low somnolence (eg, aripiprazole, asenapine, haloperidol, lurasidone, paliperidone, cariprazine). The rates of somnolence and dose and duration were positively correlated for some antipsychotics but not for others. 

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Antipsychotic-induced somnolence may be affected to various factors such as the method used to measure somnolence, patient population, study design, and dosing schedule. The mechanism of somnolence may be primarily due to the blocking of histamine 1 receptors and alpha-1 receptors. 

Further ways to manage antipsychotic-induced somnolence include adjusting doses when needed and minimizing concomitant agents that may cause somnolence. As most cases evaluated were mild to moderate, allowing tolerance to develop over ≥4 weeks is sensible before discontinuing the agent.

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