Can this drug montelukast keep you awake at night and cause some heart pulpitations?

Side effects include gastrointestinal disturbances, hypersensitivity reactions, sleep disorders and increased bleeding tendency, aside from many other generic adverse reactions. Its use is associated with a higher incidence of Churg-Strauss syndrome (whether or not this drug is 'unmasking' subclinical Churg-Strauss is as yet uncertain). In March, 2008 the FDA announced that it would investigate whether mood changes and suicidal thoughts are possible side effects of drugs in this class, including the popular drug Singulair, which currently lists these side effects.[3]

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On June 12, 2009 the Food and Drug Administration concluded their review into the possibility of neuropsychiatric side effects with leukotriene modulator drugs. Although clinical trials only revealed an increased risk of insomnia, post-marketing surveillance showed that the drugs are associated with a possible increase in suicidal behaviour and other side effects such as agitation, aggression, anxiousness, dream abnormalities and hallucinations, depression, irritability, restlessness and tremor.[4

from wikipedia.