Melatonin is a hormone secreted by the pineal gland that helps regulate the sleep-wake cycle.

Most people get enough magnesium from their diet, and while supplementation is sometimes used for anxiety, insomnia, or attention-deficit/hyperactivity disorder (ADHD), the supporting evidence is weak and based on low-quality studies.

Memantine’s indication (moderate to severe dementia only) may limit its use, but it does boast a unique mechanism of action and has some data to support its usefulness as an augmenter of donepezil.

Ambien is the original Z-drug, having been initially FDA approved in 1992.

Zaleplon is the only sleeping pill that can be taken at 3 or 4 am without causing functional impairment when the patient gets out of bed a few hours later.

Temazepam has the advantages of a short half-life and no active metabolites, and is therefore less likely to cause next day sedation. 

Suvorexant is an orexin receptor antagonist, and as such it treats insomnia differently from existing agents (though lemborexant and daridorexant have since followed in its footsteps). 

Ramelteon is a melatonin receptor agonist.