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The average individual spends about 2 hours dreaming, mostly during the second half of the night when REM (dream) cycles are longer.
Dreaming arises from signals in the pons which ascend through the thalamus into the cortex. There are also pontine signals that descend through the spinal cord causing motor paralysis. This muscle inhibition prevents motor activity during dreaming and can sometimes be lost, particularly in patients with Parkinson's disease. This entity is called REM sleep behavior disorder.
Respiratory muscles can be affected by this REM sleep paralysis. This may lead to breathing disturbances during dreaming. Changes in dreaming tendencies (e.g. "I feel like I dream all night long" or "I never dream anymore".) may be a sign of a sleep apnea or similar breathing disturbance.
Alcohol is a frequently used hypnotic in the United States. When ingested, alcohol is a potent inhibitor of REM sleep. Abstinence often causes a temporary increased in REM sleep called REM rebound. Other inhibitors of REM sleep include MAO inhibitors and tricyclic antidepressants.
Over the last year, there have been many developments in sleep medicine. New medications have been introduced treating conditions and complaints including restless leg syndrome (RLS), shift-work sleep disorder, sleepiness from sleep apnea, narcolepsy and insomnia. New research has even focused on pharmacological treatments for snoring. With the increase of sleep medications on the market, it is important to understand what these medications can and cannot do and how they are intended to be used.
Insomnia
Insomnia is the most common complaint patients have about sleep. Insomnia has received an increased attention lately with the launch of Lunesta (eszopiclone) and more recently Rozerem (ramelteon/TAK-375) and Ambien CR (zolpidem tartrate extended release). These medications join the ranks of the benzodiazepines and benzodiazepine-like drugs, anti-depressants, and anticonvulsants that are currently used to treat insomnia. Rozerem is a highly selective melatonin MT1 receptor agonist and represents a novel approach to insomnia. Because of this unique mechanism of action, it is considered to have no abuse potential and carries no DEA drug schedule.
While these medications have their niche in sleep medicine, none are indicated for use in chronic insomnia. Recently, Dr. Andrew Krystal, a sleep researcher from Duke University, demonstrated in clinical studies that Lunesta was effective for up to 6 months in patients with insomnia. This led the FDA to approve Lunesta for chronic insomnia. Lunesta, a drug similar to Ambien and Sonata, is available in 3 doses: 1 mg, 2 mg, 3 mg to more specifically tailor its effect. 1-2 mg is used for sleep-onset difficulties with 3 mg for sleep maintenance issues. Side effects are minimal and include an unusual aftertaste.
These medications should mainly be used for intermittent insomnia associated with travel (across time zones), shift-work, or isolated situations (death of a loved one, loss of a job, etc.) Like any symptom (insomnia is a symptom, not a diagnosis), the cause of the symptoms needs to be determined. Primary insomnia is exceptionally rare and should only be diagnosed after a detailed sleep evaluation.