Pheromones are airborne chemical signals that are released by an individual into the environment and which affect the physiology or behaviour of other members of the same species. The idea that humans produce pheromones has excited the imagination of scientists and the public, leading to widespread claims for their existence, which, however, has remained unproven. Here we investigate whether humans produce compounds that regulate a specific neuroendocrine mechanism in other people without being consciously detected as odours (thereby fulfilling the classic definition of a pheromone). We found that odourless compounds from the armpits of women in the late follicular phase of their menstrual cycles accelerated the preovulatory surge of luteinizing hormone of recipient women and shortened their menstrual cycles. Axillary (underarm) compounds from the same donors which were collected later in the menstrual cycle (at ovulation) had the opposite effect: they delayed the luteinizing-hormone surge of the recipients and lengthened their menstrual cycles. By showing in a fully controlled experiment that the timing of ovulation can be manipulated, this study provides definitive evidence of human pheromones.

Imprecise measures of ovulation obscure the relationship between women's sexuality and the menstrual cycle, as does studying women with different contraceptive goals in different social contexts. Here we present a novel noninvasive method to precisely pinpoint the preovulatory surge of Luteinizing Hormone (LH), demarcating hormonally distinct cycle phases with greater than 95% reliability. Women were more sexually active on days prior to and including the preovulatory (LH) surge. This pattern was evident only when women initiated sexual activity and not when their partners did, indicating an increase in women's sexual motivation rather than attractiveness. A second study replicated the 6-day increase in sexual activity beginning 3 days before the LH surge, accompanied by stronger sexual desire and more sexual fantasies. We propose the term 'sexual phase' of the cycle, since follicular phase is over inclusive and ovulatory phase is not sufficient. These findings are striking because the women were avoiding pregnancy and were kept blind to the hypotheses, preventing expectation bias. The sexual phase was more robust in women with regular sexual partners, although the increase in sexual desire was just as great in nonpartnered women, who also reported feeling less lonely at this time. We use these results to evaluate potential neuroendocrine mechanisms underlying women's sexual motivation and activity.

Approximately 14 -20 % of US adults experience gastroesophageal refl ux disease (GERD) weekly ( 1,2 ), which translates to more than 60 million adults ( 3 ). Among those reporting GERD symptoms, up to 89 % report nocturnal symptoms ( 1,4 -6 ), resulting in impairment in health-related quality of life (HRQoL) and signifi cantly worse sleep quality ( 7,8 ). Because continued sleep disruption leads to increased daytime sleepiness ( 9 ), nocturnal heartburn can reduce productivity while patients are present at work, as well as reduce function when performing normal daily activities ( 7,8,10,11 ). Th e continued presence of nocturnal heartburn despite routine medical treatment is strongly associated with decreases in HRQoL ( 12 ). In addition, the majority of GERD patients participating in a Gallup survey were not completely satisfi ed with their over-the-counter or prescription medication due to persistent nocturnal symptoms ( 6 ).Th e aims of this study were to assess, in patients with symptomatic GERD, the effi cacy and safety of dexlansoprazole MR 30 mg Nocturnal heartburn and related sleep disturbances are common among patients with gastroesophageal refl ux disease (GERD). This study evaluated the effi cacy of dexlansoprazole MR 30 mg in relieving nocturnal heartburn and GERD-related sleep disturbances, improving work productivity, and decreasing nocturnal symptom severity in patients with symptomatic GERD. METHODS:Patients ( N = 305) with frequent, moderate-to-very severe nocturnal heartburn and associated sleep disturbances were randomized 1:1 in a double-blind fashion to receive dexlansoprazole MR or placebo once daily for 4 weeks. The primary end point was the percentage of nights without heartburn. Secondary end points were the percentage of patients with relief of nocturnal heartburn and of GERD-related sleep disturbances over the last 7 days of treatment. At baseline and week 4 / fi nal visit, patients completed questionnaires that assessed sleep quality, work productivity, and the severity and impact of nocturnal GERD symptoms. RESULTS:Dexlansoprazole MR 30 mg ( n = 152) was superior to placebo ( n = 153) in median percentage of nights without heartburn (73.1 vs. 35.7 % , respectively; P < 0.001). Dexlansoprazole MR was signifi cantly better than placebo in percentage of patients with relief of nocturnal heartburn and GERD-related sleep disturbances (47.5 vs. 19.6 % , 69.7 vs. 47.9 % , respectively; P < 0.001), and led to signifi cantly greater improvements in sleep quality and work productivity and decreased nocturnal symptom severity. Adverse events were similar across treatment groups.CONCLUSIONS: In patients with symptomatic GERD, dexlansoprazole MR 30 mg is signifi cantly more effi cacious than placebo in providing relief from nocturnal heartburn, in reducing GERD-related sleep disturbances and the consequent impairments in work productivity, and in improving sleep quality / quality of life.SUPPLEMENTARY MATERIAL is linked to the online version of the paper at

The reinforcing and subjective effects of caffeine (100 and 300 mg, PO) were determined in a group of 18 normal, healthy adults. Subjects (eight females, ten males) were light to moderate users of caffeine, and had no history of drug abuse. A discrete-trial choice procedure was used in which subjects were allowed to choose between the self-administration of color-coded capsules containing either placebo or caffeine. The number of times caffeine was chosen over placebo was used as the primary index of reinforcing efficacy. Subjective effects were measured before and several times after capsule ingestion. The low dose of caffeine was chosen on 42.6% of occasions, not significantly different from chance (50%). The high dose of caffeine was chosen on 38.9% of occasions, significantly less than expected by chance, indicating that this dose served as a punisher. Both doses of caffeine produced stimulant-like subjective effects, with aversive effects such as increased anxiety predominating after the high dose. When subjects were divided into groups of caffeine-sensitive choosers and nonchoosers, a consistent relationship emerged between caffeine choice and subjective effects; nonchoosers reported primarily aversive effects after caffeine (increased anxiety and dysphoria), whereas choosers reported stimulant and "positive" mood effects. When compared with previous findings, these results demonstrate that caffeine is less reinforcing than amphetamine and related psychomotor stimulants.

No abstract