Melatonin affects sleep outcomes in research

Ezgin N, Krčum J, Šutulović N, Pavlović M, Djurić E, Mladenović D, Vesković M, Cetin AE, Rašić-Marković A, Stanojlović O, Hrnčić D · Clocks & sleep (2026)

Result: This narrative review synthesizes evidence that elevated nighttime temperatures disrupt sleep in older adults through multiple mechanisms, including prolonged sleep onset, fragmentation of slow-wave and REM sleep, and suppression of melatonin secretion. Age-related declines in thermoregulatory capacity, such as reduced sweating and impaired vasodilation, exacerbate these effects. The review notes that sex-related differences, particularly menopause-associated vasomotor instability in women and testosterone-related autonomic changes in men, further modulate individual vulnerability.

Iwasaki Y, Ohbe H, Kaiho Y, Ikumi S, Yabuki S, Wagatsuma Y, Yamauchi M, Fushimi K, Yasunaga H · Australian critical care : official journal of the Confederation of Australian Critical Care Nurses (2026)

Result: Among 1,595,351 ICU patients, 30.8% received sleep medications during their ICU stay. Sleep medication use during ICU stay was strongly associated with sleep medication prescription at hospital discharge (odds ratio: 6.90; 95% CI: 6.59-7.23), with 47.0% of users versus 11.3% of nonusers receiving prescriptions at discharge.

Yazar Kahraman EM, Uçar HN, Çetin FH, Akyürek F, Türkoğlu S · Sleep medicine (2026)

Result: In a case-control study of 29 children/adolescents with OCD and 30 matched controls, evening chronotype was significantly more common in the OCD group (p<0.05). Within the OCD group, those with evening chronotype had significantly lower CY-BOCS scores (p<0.05) and higher morning salivary melatonin levels (p<0.05), while cortisol did not differ.

Kong B, Yang Y, Song M, Yan M, Meng Y · Frontiers in cardiovascular medicine (2026)

Result: The review indicates that melatonin and its receptor agonists can improve subjective sleep quality and help regulate circadian rhythms in patients undergoing cardiac surgery. However, their effects on key clinical outcomes such as postoperative delirium, length of hospital stay, and objective measures of sleep architecture remain inconsistent across studies.

Singh B, Pigazzani F, Manfredini R · Neuroprotection (Chichester, England) (2026)

Result: This narrative review synthesizes evidence that circadian dysfunction contributes to Alzheimer's disease pathogenesis through interactions between core clock genes and neurodegenerative cascades involving oxidative stress, neuroinflammation, glial reactivity, and proteostasis. Emerging evidence suggests distinct circadian patterns in AD-relevant biomarkers, including melatonin, cortisol, orexin, core body temperature, blood-brain barrier permeability, and glial marker oscillations, which may have diagnostic and prognostic relevance.

Kalkanis A, Karkala A, Pataka A · Clocks &amp; sleep (2026)

Result: The paper argues that melatonin's clinical use is often undermined by diagnostic imprecision, inappropriate dosing, mistimed administration, inconsistent formulations, and inadequate patient counseling. It emphasizes that melatonin acts primarily as a chronobiotic whose effects depend more on timing than dose, and that supraphysiological doses and reflexive bedtime administration have become normalized despite evidence to the contrary.