Melatonin is a naturally occurring hormone produced by the pineal gland, a small structure in the brain that controls the body’s circadian rhythm — the internal clock that determines when you feel awake or sleepy.

When daylight fades, melatonin secretion rises in the evening to signal that it’s time to rest. Levels remain high throughout the night and fall again by morning, helping you wake naturally with daylight.

This daily rhythm influences:

Sleep onset and duration
Core body temperature
Hormone secretion
Metabolic processes and alertness

When the balance of melatonin is disrupted -for instance, by jet lag, shift work, or excessive evening light exposure -your body clock drifts out of sync, leading to difficulty falling or staying asleep.

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How Light and the Circadian System Interact

The master circadian clock, located in the suprachiasmatic nucleus (SCN) of the brain, receives light information from the retina. This helps synchronize the body’s internal rhythm with the 24-hour day–night cycle.

External cues known as zeitgebers (“time-givers”) -particularly light -play a major role in this process:

Morning light suppresses melatonin, boosting alertness and energy.
Evening light, especially from screens or bright LEDs, delays melatonin release and pushes sleep later.

This is why travellers crossing time zones or working night shifts often feel “jet lagged”: their SCN is still tuned to the previous time zone, not the new one.

Melatonin Receptors: MT1 and MT2

Melatonin works by binding to two main receptor types in the brain:

MT1 receptors: Encourage sleepiness and help reduce sleep latency (the time it takes to fall asleep).
MT2 receptors: Regulate the timing of the circadian phase, helping the body adjust to new time cues.

Together, these receptors ensure that melatonin not only promotes sleep but also helps resynchronize the internal clock -making it an essential tool for jet lag management and circadian adjustment.

Why Travellers Experience Jet Lag

Jet lag happens when your body’s circadian rhythm is out of sync with your destination’s local time.

For example:

Flying eastward (e.g., New York → London) shortens your day, so your body still thinks it’s earlier than it is.
Flying westward (e.g., London → Los Angeles) extends your day, delaying melatonin production and sleep onset.

The result: fatigue, insomnia, brain fog, irritability, and digestive disruption.

Using melatonin strategically can help realign your body’s clock with the new time zone more quickly.

How Circadin 2 mg Supports Jet Lag Recovery

While over-the-counter melatonin supplements are available online, Circadin 2 mg Prolonged-Release Tablets are the only MHRA-licensed melatonin medicine in the UK.

They’re formulated to release melatonin gradually overnight, closely mimicking your body’s natural rhythm. This helps maintain steady melatonin levels -ideal for travellers adjusting to new sleep–wake schedules.

Key Benefits:

✅ Supports faster body clock realignment after travel
✅ Reduces night-time awakenings
✅ Improves sleep quality and duration
✅ Helps alleviate daytime fatigue and irritability

Recommended use: Take one Circadin 2 mg tablet 1–2 hours before bedtime in the destination’s local time zone, starting on the day of travel and continuing for 2–5 nights after arrival.

💡 Tip: Combine Circadin with morning sunlight exposure and limited evening screen time for faster adjustment.

Prolonged-Release vs Immediate-Release Melatonin

Type	Duration	Effect	Best For
Immediate-Release	1–3 hours	Helps you fall asleep	Short sleep onset issues
Prolonged-Release (Circadin 2 mg)	6–8 hours	Maintains sleep through the night	Jet lag & circadian rhythm adjustment

Prolonged-release melatonin, like Circadin, offers continuous support throughout the night — particularly beneficial for those crossing multiple time zones or experiencing sleep fragmentation.

Supporting Melatonin Naturally

In addition to medication, healthy sleep hygiene supports melatonin’s natural rhythm:

Dim lights 1–2 hours before bed
Keep a consistent bedtime and wake time
Avoid heavy meals and alcohol late at night
Get morning sunlight to reinforce your internal clock
Limit blue light exposure from phones or laptops before sleep

For more lifestyle guidance, see Causes of Insomnia and Circadin and Jet Lag – Sleep Adjustment Tips.

Safety and Precautions

Melatonin is well-tolerated, but may cause mild side effects such as:

Headache
Drowsiness
Dizziness
Nausea

Avoid alcohol while using Circadin, and consult a healthcare provider before taking it if you’re:

Pregnant or breastfeeding
Taking sedatives, antidepressants, or immunosuppressants
Under 18 years of age

Frequently Asked Questions

Q1: How does melatonin help jet lag?
It helps reset your internal body clock by signaling that it’s nighttime in your destination’s time zone, promoting faster adaptation to new sleep patterns.

Q2: When should I take melatonin for travel?
Take 1-2 hours before bedtime in the destination’s local time zone, starting on the day of travel and continuing for several nights.

Q3: Can melatonin be taken long-term?
Melatonin is recommended for short-term use, such as during travel. For long-term sleep issues, speak with a healthcare professional.

Q4: What’s the difference between Circadin and regular melatonin supplements?
Circadin 2 mg is a prescription-grade prolonged-release melatonin tablet, clinically tested and MHRA-regulated -ensuring consistent quality and safety.

Key Takeaway

Melatonin is the body’s natural signal for sleep. When regulated correctly – or supported through prescription melatonin like Circadin 2 mg – it helps maintain a healthy sleep–wake rhythm and ease jet lag after long-distance travel.

By understanding how melatonin works and timing it correctly, you can reset your body clock naturally, improve sleep quality, and recover faster from time zone shifts.

Available from MedCare Health Clinic: Circadin 2 mg prolonged-release melatonin for safe, clinically proven jet lag management.