How Does Melatonin Timing Change as We Age?
It gets later through childhood and the teens, then gradually moves earlier for the rest of life. In pooled data from 121 published studies, the evening rise in saliva melatonin, called the dim light melatonin onset (DLMO), averaged about 8:00 PM in children under 10, about 9:56 PM in 10 to 19 year olds, and about 9:36 PM in people in their 20s. People in their 70s averaged about 9:13 PM, only 23 minutes earlier than people in their 20s. Men and women did not differ at any age.
Dr. Kumar’s Take
The common story is that older adults make less melatonin and release it later, so they need a supplement to “replace” it. This paper argues against both parts. Melatonin onset in healthy older people came slightly earlier than in young adults, not later. Ten of 11 studies that compared young and older people head to head found the same thing. And peak blood melatonin in people over 70 was lower, but their nightly rhythm was still strong.
The teenage delay is real. In the individual data, DLMO was about 2 hours 38 minutes later in late adolescence than in early childhood. That supports what many parents and sleep researchers have argued about early school start times.
The other finding I would take seriously is how wide the normal range is. Two healthy people of the same age can have melatonin onsets hours apart. In 12 of 14 studies of people diagnosed with delayed sleep phase disorder, the group’s average onset still fell inside that normal range. A late bedtime is not always a late body clock.
There was no sex difference either. Men and women had similar melatonin timing and similar morning or evening preference at every age.
Key Findings
- Children are earliest. Saliva DLMO averaged about 8:00 PM in children under 10 in the published studies.
- Late teens are latest. DLMO averaged about 9:56 PM at ages 10 to 19. In the individual data, 10 to 19 year olds were later than every other age group.
- Adults drift earlier, but only a little. DLMO was about 9:36 PM in people in their 20s and about 9:13 PM in their 70s, a gap of 23 minutes. The abstract puts the advance at about 30 minutes in the oldest participants.
- No sex difference. Men and women had similar DLMO in every age band, from childhood to the 70s.
- Huge spread within each age. The average standard deviation was about 1.2 hours. For people in their 20s, the reference range ran from about 6:30 PM to about 12:45 AM.
- Lab method mattered little. The type of melatonin assay and the way DLMO was calculated had little effect overall.
- Morning types rise earlier. A later DLMO went with a stronger evening preference on the Morningness Eveningness Questionnaire (p < 0.001). Morning preference increased with age.
- Delayed sleep phase disorder often looks normal. In 12 of 14 studies of people with this diagnosis, the average DLMO fell inside the normal range, though it was still later than in healthy controls.
- Older adults still make melatonin. Peak blood melatonin fell from about 72 to 61 pg/ml between the mid 20s and mid 50s, and to about 25 pg/ml by the mid 80s. People 70 and older still had high amplitude melatonin rhythms.
Brief Summary
This analysis by David Kennaway of the University of Adelaide, published in Sleep in 2023, set out to build the first reference range for DLMO. It pooled saliva DLMO from 3,579 healthy people in 121 published studies and blood DLMO from 818 healthy people in 31 studies, aged 3 to 73. For 1,749 people from 53 papers, individual DLMO values, ages, sex and questionnaire scores were obtained from the authors or from the papers. The analysis also compared lab methods, looked at people with delayed sleep phase disorder, and updated an older review of peak nighttime melatonin levels across 179 studies.
Study Design
This was a large pooled analysis of published studies, not a formal systematic review. Group averages from each study were weighted by the number of participants and grouped into 10-year age bands. Individual data shared by 34 research teams, plus data printed in other papers, were used to test age and sex effects and to set a reference range of the mean plus or minus two standard deviations for each age band. All comparisons are between different people at different ages, not the same people followed over time.
Results You Can Use
- Expect teens to run late. Melatonin onset is latest in the late teens and early 20s, so an adolescent who cannot fall asleep early is not simply being difficult.
- Do not assume older adults run late. Healthy older people had slightly earlier melatonin onset than young adults, and their morning preference was stronger.
- Treat averages as rough guides. Healthy people of the same age can differ by several hours, so a single “normal” melatonin time does not fit everyone.
- Men and women are on the same schedule. This analysis found no difference in melatonin timing between the sexes.
- A questionnaire is not a clock test. Morning or evening preference tracks DLMO on average, but the spread is too large to use the questionnaire in place of a melatonin measurement.
Why This Matters For Health And Performance
Melatonin is widely sold to older adults on the idea that they are “melatonin deficient.” This analysis found that healthy older people still have strong melatonin rhythms and that their melatonin starts slightly earlier, not later. The author also notes that at least 10 papers found no link between how much melatonin a person makes at night and insomnia. That weakens the case for taking melatonin as a “replacement.” Melatonin can still help some people sleep, but reviews suggest the effect is modest.
For people told they have delayed sleep phase disorder, the finding that most study groups had a normal average DLMO matters. It suggests some of these patients have late sleep for other reasons, and that measuring DLMO could help sort out who has a truly delayed clock.
How to Apply These Findings in Daily Life
- Work with a teenager’s clock: melatonin onset is latest in the late teens, so early bedtimes are hard to force
- Use light to shift timing: evening light delays melatonin onset and early morning light advances it
- Question “replacement” melatonin: healthy older adults in these studies still produced strong melatonin rhythms
- Ask about a DLMO test if a sleep phase disorder is suspected: a late bedtime does not always mean a late body clock
- Do not plan around sex differences in timing: men and women had the same melatonin onset at every age
Limitations To Keep In Mind
This was not a formal systematic review, and it relies on what other labs published or shared. Light levels, posture and sampling times could not be controlled across studies. More than half the studies involved people in their 20s, and only about 11% measured saliva DLMO in people over 50, so the older age groups are small. At least one study excluded healthy volunteers with a late melatonin onset, which could narrow the range. All comparisons are across different people rather than the same people followed over time. The author’s university receives payment from a company that makes melatonin assay kits, though the company had no role in the paper.
Related Studies And Internal Links
- DLMO: The Gold Standard Test for Measuring Your Circadian Clock Timing
- The Pineal Gland: Your Body’s Melatonin Factory and Sleep Control Center
- Human Circadian Clock Runs 24.2 Hours: Why We Need Daily Light Reset
- Your Brain’s Master Clock: Suprachiasmatic Nucleus Controls Circadian Rhythms
- How to Sleep Better: Science Daily Playbook
FAQs
Why do teenagers naturally stay up later than children or adults?
Their melatonin onset really is later. In this analysis, DLMO in the late teens was about 2 hours 38 minutes later than in early childhood, and 10 to 19 year olds were later than every other age group. After the late teens, melatonin onset slowly moves earlier again.
Do the sex differences in circadian timing relate to hormones?
This analysis found no sex difference in melatonin timing to explain. Men and women had similar DLMO in every age band from childhood to the 70s, and similar morning or evening preference scores.
Can these age-related changes be prevented or modified?
Melatonin timing can be shifted. Light in the evening delays DLMO and light in the early morning advances it. Melatonin taken in the evening moves DLMO earlier, and melatonin taken in the morning moves it later.
Conclusion
Melatonin onset is earliest in young children, latest in the late teens, and then moves earlier with age. The published group averages differ by about 23 minutes between people in their 20s and their 70s, but individual data from about 25 to 75 years old showed an advance of about 1 hour 20 minutes. Men and women run on the same schedule. The spread between healthy people of the same age is several hours, and most groups diagnosed with delayed sleep phase disorder still averaged inside the normal range. Healthy older adults are not melatonin deficient and do not have a late melatonin clock.
