Melatonin
Melatonin is the darkness signal—it tells your brain and body that night has arrived. Produced by the pineal gland, melatonin doesn’t generate sleep but rather signals when it’s time to sleep. Understanding this distinction is crucial for optimal use.
What Melatonin Does
| Function | How |
|---|---|
| Signals nighttime | Communicates “it’s dark” to brain and body |
| Sleep timing | Helps initiate sleep onset |
| Circadian anchor | Reinforces 24-hour rhythms |
| Antioxidant | Protects cells from oxidative damage |
Key insight: Melatonin is like the starting official at a race—it signals the beginning but doesn’t run the race. Sleep itself is generated by different brain circuits.
How Melatonin Works
The Pathway
- Light enters eyes during day
- Signal travels to suprachiasmatic nucleus (master clock)
- SCN suppresses pineal gland melatonin release
- As darkness falls, suppression lifts
- Pineal gland releases melatonin
- Melatonin signals “night” to all tissues
The Light Connection
| Light Status | Melatonin |
|---|---|
| Bright light | Suppressed |
| Dim light | Begins rising |
| Darkness | Full release |
| Artificial light at night | Inappropriately suppressed |
This is why evening light exposure disrupts sleep—it suppresses melatonin when it should be rising.
Melatonin and Serotonin
Melatonin is synthesized from serotonin:
Tryptophan → Serotonin → Melatonin
This pathway explains:
- Why morning light (boosting serotonin) helps evening melatonin
- Why mood and sleep are interconnected
- Why gut health affects both mood and sleep
Endogenous vs. Supplemental Melatonin
Natural Melatonin
- Released in precise amounts at precise times
- Responds to light/dark cycle
- Peaks 2-4 hours after darkness onset
- Declines before morning wake time
Supplemental Melatonin
| Issue | Problem |
|---|---|
| Dosing | Supplements often contain 3-10x physiological amounts |
| Timing | Taking at wrong time can shift rhythms |
| Duration | May stay elevated too long |
| Quality | Actual content varies widely from label |
When Melatonin Supplements Help
According to sleep researchers, melatonin supplementation is most useful for:
| Situation | Why It Helps |
|---|---|
| Jet lag | Helps reset circadian clock to new time zone |
| Shift work | Signals sleep time when light cues are wrong |
| Older adults | Natural production declines with age |
| Blind individuals | No light signals to regulate rhythm |
For general insomnia in healthy adults, evidence is not particularly strong that melatonin helps.
If You Use Melatonin
Recommendations based on research:
- Low dose: 0.5-1mg is often sufficient (much lower than typical supplements)
- Timing: 30-60 minutes before desired sleep
- Short-term: Not intended for indefinite use
- Quality: Choose reputable brands (actual content varies)
Higher doses don’t work better and may cause:
- Morning grogginess
- Vivid dreams/nightmares
- Disrupted sleep architecture
Protecting Natural Melatonin
Better than supplementing: protect your natural melatonin production.
| Practice | Effect |
|---|---|
| Morning sunlight | Sets circadian rhythm, primes evening melatonin |
| Dim lights after sunset | Allows natural melatonin rise |
| Avoid screens before bed | Prevents blue light suppression |
| Cool, dark bedroom | Supports full melatonin release |
See Light Exposure Protocol for details.
Melatonin Decline with Age
Melatonin production decreases across the lifespan:
- Highest in childhood
- Declines from puberty onward
- Significantly lower in older adults
This may contribute to sleep difficulties with aging. Some researchers suggest low-dose melatonin supplementation makes more sense for older adults than younger people.
Related Pages
- Circadian Rhythms
- Serotonin
- Light Exposure
- Sleep
- Apigenin (sleep cocktail component)
“Melatonin is the starting official at the 100 meter race. It calls all the sleep processes to the line and begins the race, but it doesn’t participate in the race itself.” — Dr. Matthew Walker (quoted by Huberman)