Somnolence
is a state of sleepiness where you're close to falling asleep, and may not be
able to resist the urge to doze off. As someone in treatment for bipolar
disorder or another mental illness, this can affect you since
many psychiatric medications (and many non-psychiatric medications,
too) can cause somnolence. That's why there are so many warnings about not
driving until you know how a medication might affect you, or not operating heavy
equipment when you're taking these medications. Literally, you could fall
asleep in the middle of those activities, even when you're trying hard to stay
awake. Somnolence is a medical term, but there are many other terms for the
same state of sleepiness including drowsiness, lethargic, insensible
and just plain sleepy. Medications are far from the only cause of this problem:
Some clinicians estimate that excessive daytime sleepiness may affect up to 20%
of the overall population.
Causes
There are a
variety of causes of somnolence, and not all are related to your health or to
medications you're taking. Perhaps the most common cause is simply not
getting enough sleep — studies show that people who work different shifts
that interfere with their normal sleep rhythms may be more prone to accidents
and mistakes. For example, according to the National Sleep Foundation, the
disintegration of the space shuttle Columbia and the grounding and subsequent
oil spill from the Exxon Valdez both have been attributed to mistakes made due to
fatigue. Shift workers may also be at higher risk for conditions
like heart disease and diabetes.
Other
possible somnolence causes can involve medical conditions (not treatments).
Diabetes, chronic pain, low thyroid function and other conditions may
cause excessive sleepiness. In addition, there are disorders specifically
related to sleep — sleep apnea, for example, where you literally stop
breathing for very short periods during sleep — that can interfere with your
rest and cause somnolence when you're awake. To determine what's causing your
problem, you may need an evaluation from a doctor who specializes in sleep
disorders.
Bipolar Medications That Cause Somnolence
But there's
no doubt that medications are a significant cause of somnolence, especially in
people being treated for mental health conditions such as bipolar disorder.
• Antidepressants. One of the most
common side effects reported for antidepressants is sleepiness, although some
types also can cause insomnia. People taking selective serotonin reuptake
inhibitors (SSRIs) such as Prozac (generic name: fluoxetine) or
serotonin-norepinephrine reuptake inhibitors (SNRIs) such as Cymbalta (generic
name: duloxetine) report this problem. Older tricyclic antidepressants also can
cause this problem.
• Benzodiazepines. These anti-anxiety
drugs, which include Xanax (generic name: alprazolam) and Valium (Generic name:
diazepam), also can cause severe somnolence. Medical studies have looked at the
effects of caffeine (the equivalent of two or three cups of coffee) in people
taking benzodiazepines, and have found it helps in some cases, but not all.
• Lithium. Many patients (but not
all) report getting sleepy when taking lithium for their bipolar disorder, and
in fact, tiredness and sleepiness are known side effects of the medication.
This gets better with time in some people as they adjust to its effects.
• Anticonvulsant and
anti-psychotic medications. Many of these medications cause drowsiness.
The
medications used to treat bipolar disorder affect different people in different
ways. Therefore, if you find that one drug or combination of medications is
causing somnolence, talk to your doctor about adjusting your treatment regimen.
