Excessive Daytime Sleepiness
All patients with narcolepsy have EDS and it usually the first symptom to develop. Because of it, the patient has to expend an ever greater effort on remaining awake during the daytime.
The patient may also suffer sleep attacks during which he falls asleep quite involuntarily. Indeed if he fights sleepiness and refuses to take a nap it is likely that sleep will overcome him without warning. He can also suffer 'micro-sleeps' very often without being conscious of having slept. For instance, during conversation, when another person is talking the narcoleptic can drift into sleep for as little as 30 seconds or so. When he recovers consciousness he attempts to re-enter the conversation only to find that he is 'out of synch', causing everybody else present to stare in amazement.
An important characteristic of narcolepsy is that, after having had a nap, the subject wakes feeling refreshed and able to function relatively normally for some time.
EDS can cause other symptoms such as mental 'fuzziness', poor memory, problems focusing the eyes, lack of energy and exhaustion.
Explaining Excessive Daytime Sleepiness
It is very difficult for the normal person to accept excessive daytime sleepiness as being out of the patient's control. The unaffected see the patient's sleepiness as an insult, a rejection, or evidence of a lack of interest. Family members equate the patient's pathological sleepiness with their normal experience of sleepiness and assume that the patient could "fight it off" if he or she really wanted to. The spouse and family members must clearly understand that this symptom is totally outside the control of the patient's volition or willpower. This point must be made with great firmness. Even family members with a rudimentary understanding of the disorder often conclude that the patient "just isn't trying hard enough".
Further to confuse the situation, the patient with narcolepsy may be capable of staying awake and alert, and may even become animated, during occasional, unique and/or stimulating circumstances. Family members, who see the patient responding with animation to an unusual guest, experience, or situation, tend to assume erroneously that the patient should always be capable of 'willing' the same level of alertness. For instance one narcoleptic patient attended a symposium on sleep disorders held out of town. Although he normally naps frequently and has little energy or enthusiasm during the day at home, he was able to remain wide awake and alert almost all day at the symposium (He napped for half an hour in the afternoon). This reinforced his wife's conviction that he could always stay awake if he were really interested in their home life.
Our experience with thousands of patients is that this is not correct. The normal correlation which exists between interest and wakefulness simply does not hold for those suffering from narcolepsy. Assuming that the person with narcolepsy could fight it off if he really wanted to is as illogical as assuming that no one need ever sleep because some people are able to fight off sleep during unique (Christmas Party) or emergency (fire) situations.
The symptoms must be defended as manifestations of a disorder, and not signs of a willful lack of effort. Without firm and knowledgeable counselling on the part of the physician, family members are often unable to accept sleepiness as part of the illness.
Until relatively recently EDS was only treated with amphetamine-like central nervous system (CNS) stimulants. The compound most commonly used in the UK is dexamphetamine sulphate (dexamfetamine sulphate, Dexedrine). Other possibilities are methylphenidate (Ritalin), the most commonly used drug in the USA, and mazindol (Teronac). Unlike, dexamphetamine, neither of these latter two medications are licensed for the treatment of narcolepsy.
Please note that, at present (November 2008), mazindol is no longer available in the UK. As soon as the situation changes further news will be posted on this page.
In 1998 a drug of quite a different type was introduced into the UK and is available on prescription. This is modafinil, marketed under the name Provigil. This drug works in a different way to the CNS stimulants and is regarded as a wake-promoter.
Recently a new drug, sodium oxybate (Zyrem), has been introduced to treat EDS. This drug is interesting as it is also licensed to treat cataplexy - another important symptom of narcolepsy. Unlike previous drugs used to treat narcolepsy sodium oxybate does not appear to be a stimulant of the CNS nor a wake promoter. Its mechanism of action is, at present, unknown although it may be related to an improvement in the quality of night-time sleep which results from taking this drug. This medicine is taken at night, often in divided doses.
Some doctors may treat EDS with a combination of two or more of the drugs discussed above.
Other potential treatments are currently being studied. Drugs which mimic the effects of hypocretins (orexins) are being developed which may eventually be used clinically. Another line of research involves drugs called histamine H3 antagonists. These agents increase the amount of histamine released from nerve endings in certain parts of the brain. Histamine produces arousal and so the H3 antagonists might be expected to be of use in the treatment of EDS associated with narcolepsy. The first of these H3 antagonists to be tested on subjects with narcolepsy, triprolisant (BF2.649), has been shown to reduce markedly excessive daytime sleepiness. Another H3 antagonist, ciproxifan, is to be tested clinically in narcoleptic subjects.
Intravenous immunoglobulin has been shown, in preliminary studies, to reduce the symptoms of narcolepsy, particularly when given soon after the first symptoms have developed. Furthermore, in a narcoleptic subject with low CSF hypocretin the administration of immunoglobulin resulted in a normalisation of hypocretin concentrations. Immunotherapy may prove to be a useful form of treatment in the future.
Before taking any prescribed medication it is very important that patients read the Patient Information Leaflet packed with the medication. This summarises, in lay people's language, information relating to the efficacy and safety of the medicine. It will also list the side effects which have been observed in patients taking the drug. Patients should avoid stopping treatment without discussion with their doctor or pharmacist.
For more detailed information on these drugs see the Narcolepsy association's booklet "Narcolepsy - a patient's guide to treatment". Click here to download an application form to purchase this booklet.
Note: pregnant or nursing mothers should discuss with their doctor the advisability of taking these drugs.