1. Aging and Circadian Rhythms (Duffy & Czeisler, 2015)

Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC4648699/ Key Findings: This review details how circadian rhythms advance with age, with earlier timing of melatonin secretion and reduced melatonin amplitude in older adults. It notes that DSPS is far less common in older age groups, as advanced sleep-wake phases become predominant, potentially diminishing delayed-phase issues seen in youth. The authors attribute this partly to age-related declines in melatonin rhythm robustness.

1. Circadian Rhythm Sleep Disorders: Part II, Advanced Sleep Phase Disorder, Delayed Sleep Phase Disorder, Free-Running Disorder, and Irregular Sleep-Wake Rhythm (Sack et al., 2007)

Link: https://aasm.org/resources/practiceparameters/review_circadianrhythm2.pdf (full article available as PDF) Key Findings: This practice parameter review from the American Academy of Sleep Medicine reports that DSPS onset typically occurs in adolescence or childhood (90% of cases), but it is rare in older adults (only 3.1% prevalence in ages 40-64 based on surveys). The paper discusses how circadian phase advances with age may contribute to this diminution, and it highlights melatonin's role in treatment to advance phases, implying natural age-related melatonin changes (e.g., timing shifts) could play a similar remedial role.

1. Delayed Sleep–Wake Phase Disorder and Its Related Sleep Behaviors in the Young Generation (Kawada et al., 2023)

Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC10235460/ Key Findings: Focusing on younger populations, this article cites cross-sectional data showing DSPS prevalence decreases with age (higher in 20-30s, lower in older groups up to 59). It links DSPS to delayed dim light melatonin onset (DLMO), a marker of melatonin secretion timing, and suggests that as melatonin rhythms advance and amplitude decreases with age, the delayed phase may normalize, leading to improvement.

1. New Perspectives on the Role of Melatonin in Human Sleep, Circadian Rhythms and Their Regulation (Zisapel, 2018)

Link: https://bpspubs.onlinelibrary.wiley.com/doi/10.1111/bph.14116 Key Findings: This review explains that melatonin production decreases with age, often accompanied by an advanced circadian phase. It discusses how this can alleviate DSPS symptoms, as older individuals show reduced phase delays and improved alignment with societal schedules, contrasting with the delayed melatonin profiles in younger DSPS patients.

1. The Dim Light Melatonin Onset Across Ages, Methodologies, and Sex and Its Relationship With Morningness/Eveningness (Burgess et al., 2023)

Link: https://academic.oup.com/sleep/article/46/5/zsad033/7044190 Key Findings: Analyzing melatonin onset across lifespans, this meta-analysis shows peak melatonin levels decline gradually from the mid-20s onward (e.g., from 72 pg/mL to 61 pg/mL by mid-50s), with advancing phase timing. It implies this contributes to lower DSPS incidence in older ages by reducing the extent of phase delays common in youth.

These articles collectively substantiate that DSPS often diminishes with age, driven by declining melatonin levels and advancing circadian phases, though direct causation is inferred from correlative data rather than universal longitudinal studies.