Yohimbine is an indole alkaloid derived from the bark of the African yohimbe tree (33). Yohimbine has been noted to treat fatigue, depression, diabetes, and sexual dysfunction. A meta-analysis of seven placebo-controlled trials (34) deemed yohimbine superior to placebo for the treatment of ED with rare adverse events. The proposed mechanism of action (35) is via the inhibition of central alpha-2-adrenergic receptors, decreasing central inhibition of arousal, and increasing penile nerve stimulation resulting in increased NO. Common side effects include headache, sweating, agitation, hypertension and insomnia. Contraindications include patients on tricyclic antidepressants, anti-hypertensives and central nervous system stimulants.
Penile vibratory stimulator is a battery operated device with oscillating discs that can provide excitation of afferent penile nerves at various regulated frequency and amplitudes. PVS has been utilised to activate the ejaculatory reflex for patients with spinal cord injury above T10 seeking to collect retrogradely ejaculated semen in fertility treatment (10). The Viberect is a vibratory stimulation handheld device approved by FDA for treatment of ED. It is clamp-shaped with two oscillating discs facing each other near the tips, and the glans penis is placed between the two oscillating discs to receive concurrent dorsal and ventral stimulation at adjustable frequencies and amplitudes.
L-arginine is an amino acid that is necessary for the lining of the blood vessels to produce nitric oxide. Nitric oxide allows the blood vessels to relax, thus improving blood flow throughout the body, including to the penis. Studies on L-arginine and erectile dysfunction have used between 2,000-5,000 mg a day in divided doses.ii Supplemental arginine is best taken on an empty stomach.3
Poor sleep patterns can be a contributing factor for erectile dysfunction, Mucher says. One review published in the journal Brain Research emphasized the intricate relationship between the level of sex hormones like testosterone, sexual function, and sleep, noting that testosterone levels increase with improved sleep, and lower levels are associated with sexual dysfunction. Hormone secretion is controlled by the body’s internal clock, and sleep patterns likely help the body determine when to release certain hormones. 
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