Caffeine reversal of sleep deprivation effects on alertness and mood.

This study assessed the ability of high doses of caffeine to reverse changes in alertness and mood produced by prolonged sleep deprivation. Fifty healthy, nonsmoking males between the ages of 18 and 32 served as volunteers. Following 49 h without sleep, caffeine (0, 150, 300, or 600 mg/70 kg, PO) was administered in a double-blind fashion. Measures of alertness were obtained with sleep onset tests, the Stanford Sleepiness Scale (SSS), and Visual Analog Scales (VAS). Sleep deprivation decreased onset to sleep from a rested average of 19.9 min to 7 min. Following the highest dose of caffeine tested, sleep onset averaged just over 10 min; sleep onset for the placebo group averaged 5 min. Scores on the SSS increased from a rested mean of 1.6-4.8 after sleep deprivation. Caffeine reduced this score to near rested values. Caffeine reversed sleep deprivation-induced changes in three subscales of the POMS (vigor, fatigue, and confusion) and produced values close to fully rested conditions on several VAS. Serum caffeine concentrations peaked 90 min after ingestion and remained elevated for 12 h. This study showed that caffeine was able to produce significant alerting and long-lasting beneficial mood effects in individuals deprived of sleep for 48 h.

Cutaneous and pulmonary reactivity in cholinergic urticaria.

Cutaneous and pulmonary reactions to mediators of inflammation were studied in twenty-one patients with cholinergic urticaria, in twenty patients with other types of urticaria, and in seventeen healthy controls. Compared with controls and patients with moderate disease, patients severely affected by cholinergic urticaria or other types of urticaria developed larger weals at sites of injection with histamine (9 X 10(-7) M), but not with compound 48/80 (0.1%), acetylcholine (7 X 10(-5) M), kallikrein (4 X 10(-10) M). On bronchial challenge with acetylcholine (7 X 10(-5) M), pulmonary resistance increased markedly only in severely affected cholinergic urticaria patients. There was no correlation between cutaneous and pulmonary reactivity in individual subjects. Patients with cholinergic urticaria therefore demonstrate features of heightened skin reactivity (shared by patients with other urticarias) and an increased bronchial reactivity (as found in latent asthmatics).