African trypanosomiasis or sleeping sickness is a complex disease that involves a constellation of symptoms, but is hallmarked, during disease progression, by the onset of disturbances of sleep/wake alternation during 24 h and by alterations in the organization of sleep. In particular, the patients develop frequent and sudden sleep episodes during the day, and wakefulness episodes during night. A striking feature of the illness is represented SOREM (sleep onset rapid eye movement) episodes, in which the patients go directly from wakefulness to REM sleep without passing through non-REM sleep. Similar alterations have been found in Trypanosoma brucei brucei-infected rats, and we are now documenting a relatively early onset of SOREM episodes during the experimental infection. In trypanosome-infected rats, the number of SOREM episodes increases over time and reaches a peak which is coincident with intrusion of sleep into wakefulness and vice versa. We are currently investigating whether the latter changes can help in disease staging by revealing parasite passage across the blood-brain barrier (BBB) and invasion of the brain parenchyma.