Understanding Narcolepsy

By Jeimylo C. De Castro, MD

IN the face of this fast-changing urbanized community, it is hard to realize that people can still doze off to sleep. In fact, with the onset of the BPO, many new graduates throng to these centers to get their jobs, most with the aim of honing well their command of the English language as their mode of communication. Sleep, in fact, seems to be just an alternative to them. In my medical college days, sleeping is considered a luxury. You are fortunate to find enough time to sleep after a busy duty hours in the hospital while on training, only to find out upon waking up that it’s time to report for duty again.

Sleep is important to life. We need at least 7 to 8 hours of sleep per day to have a restorative sleep. Babies need more time sleeping while adults need to incur a restful sleep of about 8 hours a day. As we grow old, the amount of time spent sleeping declines.

Narcolepsy is a pathologic condition characterized by an unusual daytime sleepiness and fatigue. It is the second leading cause of daytime sleepiness after obstructive sleep apnea. What is very disturbing in this pattern of sleepiness is its inappropriate onset in any part of the day and can happen repeatedly during the day. We all have our share of intense urgency to sleep usually if the environment is conducive for sleeping with mild soothing music around and the lights are dim and subdued. But while it is true that we all feel that drowsiness sometimes, a narcoleptic individual will show other associated abnormal patterns of sleep. For instance, although they slept during daytime and doze off easily, their nighttime sleeping patterns are fragmented with intermittent waking hours.

A normal sleep is usually made up of a series of two alternating events called non-rapid-eye-movement (NREM) sleep and rapid-eye-movement (REM) sleep. In a normal adult, we pass through these cycles for four to five times each time in the evening when we sleep for an average of 8 hours. These events during sleep are based on the fact that different brain activities with the help of electrodes are recorded in the brain. Under the NREM, we have four different stages (1 to 4), with the stage 1 being light sleep and stages 3 to 4 being deep sleep. In stage 3 or 4, no muscle movement takes place and it is very difficult to wake up someone at this point. More delta brain waves appear in stage 4 which distinguishes it from stage 3. It takes about one and a half hour to be able to complete one cycle from NREM sleep to REM sleep. REM sleep which represents 20–25 percent of our sleeping time is characterized by a rapid movement of the eyeball, increase heart rate and breathing, with the blood pressure tending to rise at the same time. The brain activity during this stage is said to approximate that of the waking period and coincides with dreaming. The REM period lengthens towards the duration of the sleeping periods. However, in an extremely sleepy individual, the REM sleep is usually shorter to sometimes absent.

In our simple appreciation of the normal sleeping patterns, a narcoleptic individual will show more than his extreme tendency to fall asleep. Although what is obvious here is the daytime sleepiness which is present in the majority of patients, other manifestations may include a sudden and temporary loss of muscle tone associated with an emotional reaction unique to this disease referred to as cataplexy. It is typically characterized by buckling of knees, jaw or head dropping upon laughing or anger or any other emotions. Visual and auditory hallucinations is also present occurring both while falling asleep or even upon waking up. And, of course, patients may show what is referred to as sleep paralysis, a phenomenon occurring in this patient characterized by inability to move any part of the limb or body while falling asleep or even upon waking up. These observable presentations of patients with narcolepsy may not be present in patients with these suspected problems and as such it is very difficult to make the diagnosis early on. In fact, patients may refer to one of these symptoms many years back, in their teenage years with a mean of 14 years on the average before the right diagnosis is reached. Many still are left undiagnosed. As it is, many would not take these symptoms as indicating any pathologic conditions. To some extent the interference to their social and academic performance may be one reason why persons with narcolepsy would seek for medical attention. The impact of this disease to one’s professional or personal development may be too much considering that as the full-blown symptoms appear, it means that it has existed many years already.

So what could be the cause of all these signs and symptoms? Is there a familial tendency to this disease? Research done among narcoleptic animals like Dobermans and Labradors shed light to how these affects human alike. It revealed a neurotransmitter in the brain called hypocretin, which is said to be deficient in humans with narcolepsy. Hypocretin modulates activity in the hypothalamus in the area responsible for sleep. Although this substance in recent studies do not yield an abnormal level to warrant its deficiency as a direct cause for narcolepsy, the genetic predisposition present may influence the abnormal functioning of hypocretin in the brain.

It is easy to diagnose if all symptoms are present which more often are not present. However, to test this requires a sleep laboratory. A nocturnal polysomnogram is done followed by multiple sleep latency test (MSLT). The test will confirm by showing a short sleep latency of usually less than 5 minutes and also an abnormally short latency prior to the first REM period (SOREMPs). It takes 10 to 20 minutes for a normal person to fall asleep. More than two
SOREMPs and a sleep latency of less than 5 minutes strongly suggest narcolepsy. The CSF hypocretin test has yet to become a routine laboratory test. For some centers, a Epworth Sleepiness Scale is an 8-scale questionnaire to determine excessive sleepiness.

Treatment for narcolepsy could best be addressed if identified and treated early on. But as mentioned earlier the diagnosis for narcolepsy takes years to be detected. As it is, treatment is not solely based on the medications but there are guidelines that a patient must follow even at home. This includes a scheduled sleeping calendar, which if directed by a sleep medicine specialist can help a lot regulate the sleeping patterns. Also avoid caffeine-containing drinks and alcohol as these could interfere with sleep patterns. Exercise program must also be designed to help regulate the tendency to sleep during daytime and for safety reasons one must avoid driving as this might result to accidents. On the medications, the goal of treatment is to control excessive daytime sleepiness using stimulants of the central nervous system which includes methylphenidate and modafinil and antidepressants to reduce cataplectic attacks like tricyclic antidepressants. Other available medications like fluoxetine are also used for cataplexy.

Narcolepsy is a disease that could be socially and professionally embarrassing if left untreated. Its impact may interfere with work and social activities. Despite its early onset and late diagnosis, this disease can be properly managed by sleep medicine specialists, and thus could provide patients with productive and meaningful life through the years.