When any one is affected by African sleeping sickness, he wants to sleep at all times. We observed the case of an officer of the Belgian Congo Army, suffering from this sickness, who actually fell asleep over his soup while at table. Dr. Willems, of Brussels, also mentions a case of a patient who fell asleep during his wedding, and of another who went to sleep on the doorstep while in the act of calling on him for advice.
Discovery of the cause of such a marked degree of sleepiness caused by disease should be of the greatest possible assistance in solving the mystery which enshrouds the lesser degree of sleepiness found in normal cases. We will, therefore, now discuss the question of the cause of the uncontrollable desire to sleep in cases of sleeping sickness.
As we pointed out in a communication to the German Congress of Medicine in Wiesbaden, in 1905, sleeping sickness is clinically and essentially a condition quite different to trypanosomiasis. It undoubtedly is the consequence of the former, which is caused by the bite of the tsetse fly (Glossina Palpalis); but sleeping sickness presents entirely different clinical symptoms from the first, and it also takes a much longer time, sometimes five to seven years, to develop, after the preceding trypanosomiasis.
As we could not fail to observe, the above case presented all the appearances of a myxœdematous condition, among others the same walk, slowness of movement and of speech, and the same apathetic mental state, with the same dullness of memory; and it was surprising to witness how all these symptoms improved only a few days after thyroid treatment had been instituted.
The pathological and anatomical changes in patients suffering from African sleeping sickness, described by the English and Portuguese Commission charged with the study of this disease, present also a great similarity to the changes found in myxœdema, and this is especially the case in connection with the central nervous system. Thus we find in both conditions similar changes, such as destruction of the nerve cells and nerve processes, chromatolysis, disappearance of the Nissl bodies, and also the same typical agglomeration of white blood-corpuscles in and around the blood-vessels, etc. The most striking point in reference to this similarity is the fact that the condition in the central nervous system is in both conditions named alike, viz., pylo-encephalo-myelitis. Walter Edmunds has found similar changes in dogs and monkeys after removal of the thyroid.
This singular similarity also coincides with the etiology of the two conditions. Myxœdema is most often the consequence of a previous infectious disease; in the case of sleeping sickness, this previous infectious disease is trypanosomiasis. In trypanosomiasis we find all the symptoms of Graves’s disease. In the chapter on the agencies which grant us immunity against infections and intoxications, we explain the presence of the symptoms of Graves’s disease. The symptoms of trypanosomiasis can be explained in the same way, as can those which occur in other infectious diseases, as they are expressions of the defense of the thyroid against infection. The consequence of such overwork of the thyroid is its degeneration, which results in the symptoms of a myxœdematous condition, as found in sleeping sickness.
According to Koch, arsenic, in the form of atoxyl, can give good results in such a condition; but with arsenic we introduce one of the main elements contained in the thyroid gland, and arsenic can also afford favorable results in the treatment of myxœdema.
The most typical symptom of African sleeping sickness is the great somnolence which cannot be controlled or resisted, as stated in the few examples given above. This somnolence is also one of the typical symptoms of myxœdema, being according to Pilcz, one of the four cardinal symptoms of this disease. We also find this in animals or persons in which the thyroid has been removed. We have observed dogs in which this has been done, and they were always so fast asleep that the loudest noise could not rouse them. From the foregoing there can be no doubt that the thyroid gland has something to do with sleep, and this is best exemplified by the circumstance that there is sleepiness in all those conditions where the thyroid gland is degenerated, as in the instances, just quoted, of myxœdema and of animals in which the thyroid has been removed. In addition to these examples, sleepiness can also be observed in cases of tumors of the pituitary body—for instance, in acromegaly. However, as has been shown by Gley, Rogowitsch,[329] Stieda,[330] Sajous,[331] and others, the pituitary gland and the thyroid are in a very close relationship, and, as I have also pointed out in a previous paper, we find pretty constantly alterations of the thyroid gland in acromegaly. Salmon also mentions that in tumors of the pituitary body, with sleepiness, there was generally found an atrophic condition of the thyroid.
Sleepiness is frequently observed in certain cases of obesity. Such a condition was described several years ago, under the name narcolepsy, by Sainton. I have also observed similar cases. Thus, an English patient of mine, a gentleman weighing 260 pounds, would fall asleep on any occasion—in church, at the theatre, and at concerts; and I have heard of a similar case from a confrère (related to me by Dr. Echlin, of Ottawa), who was a very fat man and who snored much louder during an operation than did the narcotized young lady, whom Dr. Echlin was operating on for appendicitis.
The sleepiness in these cases must also be attributed to the thyroid gland, which governs metabolism, as shown by the researches of Prof. Magnus-Levy,[332] of Berlin, Thiele, Nehring, etc., and also by my own works. The fat-reducing action of thyroid extracts confirms this clearly.
Sleepiness is a frequent symptom of chlorosis; and it is a fact that in chlorosis the thyroid is very often altered, which might thus explain it.
Sleep produced by narcotics and alcohol can also be brought in relation with altered thyroid functions. We have already mentioned that we have observed during narcosis with chloroform and ether a marked swelling of the thyroid gland, indicating a condition of hyperactivity, which is followed by exhaustion; and after previous mental excitation, depression and sleep follow. The action of alcohol on the thyroid has also been explained in a previous chapter on alcohol.
The sleepiness we notice after a heavy dinner, and more particularly after partaking of a large amount of meat, can also be traced to thyroid changes; for we know that the thyroid gland destroys toxic products formed in the intestines, especially those toxines caused by the destruction of albuminoids, as shown by Blum.
The best proof, however, of the truth of the assertion that a degenerated state of the thyroid produces sleepiness, is to be found in the fact, which we have established by a number of observations on patients, and also on ourselves, that the serum of animals, in which the thyroid has been removed, causes sleep. We will deal more fully with this in our next chapter on the treatment of sleeplessness.
If sleepiness is so frequent in all degenerative changes of the thyroid, on the other hand insomnia is the rule in cases of hyperactivity of the thyroid gland, as in Graves’s disease, in which we know there exists a condition of hyperactivity of the thyroid. We also find insomnia in diabetes, but only in the preliminary stages, where there is no acetone and diacetic acid in the urine. In severe cases we often find, on the contrary, sleepiness; and this may be attributed to the fact that severe cases of diabetes present features of a myxœdematous condition, as we have found by the disappearance of the acetone and diacetic acid through treatment with thyroid extracts. Sleeplessness can also be produced artificially by giving thyroid preparations in large quantities.
If sleepiness may be produced by thyroid degeneration, and sleeplessness through thyroid hyperactivity, the conclusion is not unjustified that the thyroid exerts a controlling influence upon sleep; it is, however, quite possible that the other ductless glands may also influence sleep.
Subsequently to my communication to the German Congress of Internal Medicine in 1905, wherein I showed that the thyroid governs sleep, Dr. Salmon, of Florence, in a monograph on sleep, tried to show, without any knowledge of my communication, that sleep is governed by the pituitary body. As, however, the pituitary body and the thyroid are in close relationship, and as Salmon also mentions that in cases of tumors of the pituitary body the thyroid has been found atrophic, I am inclined to attribute the primary rôle to the thyroid. We can produce sleepiness by the serum of thyroidectomized animals, and sleeplessness by thyroid extracts; but we do not yet know any similar facts about the pituitary body.
From the communications of various authorities, it appears possible also that the adrenals influence sleep as first pointed out by Professor Sajous in 1903 in the first volume of his work (p. 520) on the Internal Secretions. Dr. Zeigan[333] injected a milligramme of adrenalin, mixed with 5 grammes of physiological salt solution, into the vicinity of the brain of cats, producing, within one minute, a deep sleep lasting from thirty to fifty minutes; and when the cats awoke they remained very drowsy for some time afterward.
From the above observations therapeutic conclusions may also be deduced, as we will show in the chapter on the treatment of sleepiness and sleeplessness.