. It is found in coffee, of course, but also in tea, chocolate-flavored products and cola-based beverages, etc. 1 Due to its behavioral and psychomotor stimulating properties, it is used to maintain vigilance, memory, and performance levels during limited sleep deprivation. [2][3][4][5][6][7][8] Some prolonged sleep deprivation and wake-sleep rhythm disruptions are common in everyday life, especially in emergency cases, during rescue operations, in the army, or during transmeridian flights. These situations lead to a certain number of vigilance and performance alterations, which in turn lead to a decrease in efficacy or to the onset of penalizing symptomatology. [9][10][11][12] However, the results obtained with the use of caffeine to increase vigilance and performance level vary greatly. Sometimes, the results are very positive; an increase in performance mainly in visual vigilance tasks 13 can be observed as well as an increase in the level of awakeness-measured by electrophysiological techniques 2 -for unusual situations such as night work. Other studies reported an absence of effects or heterogeneous results 14 and sometimes negative effects such as the onset of tolerance during repeated intake of caffeine 15 or the onset of anxiety with still relatively low doses (325 mg). 16 In a general way, all the studies selected from a bibliographic research report an unquestionable stimulating and awaking effect of caffeine, but the effect has a limited power-especially compared with amphetamine-and duration. 17,18 Moreover, repeated caffeine intake can lead to the onset of deleterious cardiovascular or neurological side effects when the dose exceeds 600 mg. Therefore, it seemed interesting to assess the effects of a new galenic form of caffeine called " slowrelease " caffeine (SR caffeine) Stinergic. The release of Study Objectives: The aim of this study is to assess the interest of the intake of a new galenic form of caffeine called " slowrelease " caffeine (SR caffeine) during a decrease of vigilance due to a limited sleep deprivation. Design: The controlled method used compared three doses of SR caffeine (150, 300 and 600 mg) with a placebo. Tests were performed 2, 9 and 13 hours after each treatment. Wakefulness level was assessed subjectively through questionnaires and analog visual scales, and objectively with the Multiple Sleep Latency Test. Performance level was also assessed regularly with an attention test, a grammatical reasoning test, a spatial recognition test, a mathematical processing test, a visual tracking test, a memory search test, and a dual task. The motor activity was evaluated by wrist actimeter and safety of treatment was observed by regular clinical examination. Setting: NA Participants: Twenty-four young and healthy volunteers (12 men and 12 women) participated in a 32-hour sleep deprivation. Interventions: NA Results: The results show a significant effect of slow-release caffeine vs. placebo, and on vigilance and performance when subjects became tired. The effects of SR caffeine lasted 13...