Definition

• Effexor is the brand name for the drug velafaxine, which is a popular antidepressant of the serotonin-norepinephrine reuptake inhibitor (SNRI) comprised of a phenylethylamine structure. In 2007, Effexor was prescribed to 17.2 million people in the U.S. retail market. It is typically used to treat generalized anxiety disorder, social anxiety disorder, major depression and panic disorder in adults. It is not approved by the FDA for use in children and adolescents because of its potential to increase attempts and events of self-harm and thoughts of suicide.
  
  

Process

• As a SNRI, Effexor functions by blocking transporter "reuptake" proteins for important neurotransmitters (hormones) that affect mood. This leaves more active neurotransmitters in the synapse and an increase in how many of these mood hormones are used. The three neurotransmitters affected are serotonin (also known as 5-hydroxytyrptamine), norephinephrine (noradrenaline) and, to a lesser extent, dopamine. Low levels of these hormones have been associated with depression. SNRIs inhibit the reuptake of these hormones, which would typically lead to the neurotransmitters being taken back into body storage for later use. With an increase in usable serotonin, norephinephrine and dopamine, the mood of the patient rises.
  
  

Effexor and Sleepiness

• The change in levels of these hormones has been shown to increase fatigue. Serotonin, while not created or manipulated during sleep, has been shown to increase central fatigue in times of increased activity. Effexor would increase this activity by blocking the transporter proteins. A 2001 Stanford University Medical study showed a connection between dopamine and the regulation of sleep. A lack of dopamine has been linked to the jitteriness in diseases like Parkinson's, and an abundance of dopamine may cause the opposite, lethargy or tiredness. Lastly, a decrease in norepinephrine has been shown to reduce or remove the ability to enter REM sleep. An increase, as would happen with the medication Effexor, may lead to longer and a quicker entry into REM sleep. Since there have been only a few studies about how these hormones affect sleep when their abundance is combined, some of these reasons for fatigue are speculation based on independent studies where only one hormone is tested. In several cases, the initial side effects of Effexor, like sleepiness, faded after a month of taking the medication.