DISTRIBUTION OF SLEEPING AND WAKING IN AF RICAN SLEEPING SICKNESS

Last century, patients with human African trypanosomiasis were describ ed as sleepy by day and restless by night, and physicians refered to t his condition as sleeping sickness. Such a description could have evok ed a disturbance of circadian rhythms. However, it is only in 1989 tha t the first 24-hour recording was performed by our team in Niamey (Nig er) in a patient with sleeping sickness. The patient was a Niger-born farm worker who had contracted the disease near Gagnoa (Cote d'lvoire) . Polysomnographic recordings (electroencephalogram, EEG, electrooculo gram, electromyogram, electrocardiogram, buccal and nasal airflow, and chest respiratory movements) showed a disappearance of the circadian distribution of sleep and wakefulness, which fended to occur evenly th roughout day and night, with a sleep-wake alternation of approximately 80 minutes. Two investigations were conducted thereafter. The first o ne was done at Daloa (Cote d'lvoire) in 8 patients who were recorded d uring two 24-hour periods, with and without hourly blood samples the s econd at Brazzaville (Congo) in 10 patients recorded for 24 hours befo re and after treatment with melarsoprol. Aii patients were at the stag e of early meningoencephalitis. At Daloa, polysomnographic recordings were taken on two 8-channel EEG machines (Alvar Minihuit, and T3-ECEM) , as well as on a portable Oxford Medilog 9000 system from the same el ectrodes. Sleep and wake structure was altered in the most severely si ck patient, the EEG trace being loaded with slow waves. Stages 1 and 2 , and stages 3 and 4 could not be distinguished from one another. In t he other patients, all sleep stages were easily scored. No difference was seen between recordings, regarding blood collection. All patients presented a marked disturbance in the circadian organisation of their sleep-wake cycle, this alteration being proportional to the severity o f the disease. A 17-year-old patient presented a 90-minute periodic oc currence of REM sleep throughout the nychthemeron. These results were confirmed in another 10 patients recorded at Brazzaville, using 2 Alva r Minidix and two portable Oxford Medilog 9000 II systems, with contin uous blood withdrawal. wrist actimetry was also taken. In parallel wit h the major circadian disturbance in the sleep-wake cycle observed in the most severely sick patients, wrist actimetry proved to be unable t o distinguish between rest and activity episodes. These circadian dist urbances were improved after the first melarsoprol treatment. The alte ration of the circadian rhythmicity of sleep and wakefulness was not f ound in 6 healthy volunteers recorded in the same experimental conditi ons with an intravenous catheter to collect blood every 10 minutes. In conclusion, at the stage of meningoencephalitis, human African trypan osomiasis, sleeping sickness, represents a dysregulation of the circad ian rhythm of the sleep-wake cycle, rather than a hypersomnia, which m ay be related to a functional and reversible alteration of the circadi an body clock.