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Listen to the full interview with Dr. Leon Lack in Episode 173 of the Fibromyalgia Podcast®
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Originally shared in Episode 173 of the Fibromyalgia Podcast®, adapted for readers of The Fibro Compass℠.
Your body runs on a rhythm — and when that rhythm slips, sleep, pain, and energy slip with it.
How circadian rhythm affects pain, fatigue, mood, and flares — and what you can do to get back in sync.
For many people with fibromyalgia, sleep problems are one of the biggest daily hurdles. You may feel tired all day, wide awake at night, or stuck in an unpredictable pattern where you can’t fall asleep at a normal time — and then can’t wake up when you need to.
Many of us blame stress, pain, or habits. But there’s another major player most people don’t know about…
Your circadian rhythm — your body’s internal clock.
When this clock gets out of sync, it affects everything from your sleep and energy to your pain levels and mood. And for those of us with fibromyalgia, that disruption often hits harder and takes longer to recover from.
Recently, I interviewed Professor Leon Lack from Flinders University and the Adelaide Institute for Sleep Health, one of the world’s leading experts on sleep and circadian rhythms, on Episode 173 of the Fibromyalgia Podcast®. Together we explored how your body clock works, why light plays such a powerful role, and what you can do (even in winter!) to help your rhythm run on time.
Here’s what you need to know.
What Your Circadian Rhythm Actually Is (And why it matters for fibromyalgia)
Your circadian rhythm is a 24-hour internal timing system that tells your body when to feel awake, when to feel sleepy, how alert you are, and even how well you tolerate pain.
Think of it as a built-in schedule your body is always trying to follow.
This rhythm:
- boosts energy and alertness in the late afternoon
- slows your body down in the evening
- lowers your temperature and metabolism at night
- prepares you to wake up as morning approaches
But here’s the tricky part: your body clock is slightly longer than 24 hours.
On its own, it naturally drifts later and later.
That means you need a daily reset—something that tells your brain, “This is morning. Start the day.”
And that something is light.
Why Light Is the Most Powerful Signal Your Body Gets
Bright light, especially in the morning, sends a direct message from your retina to the part of your brain that controls your body clock.
This morning light does three important things:
- Stops your body clock from drifting later
- Helps set your “alert zone” earlier in the day
- Supports better sleep that night
Without morning light—especially in winter or in a dark climate like Seattle—your clock slips later. And that delay ripples into everything:
- Trouble falling asleep
- Trouble waking up
- Feeling groggy or “hungover” in the morning
- Brain fog
- Mood dips or seasonal depression
- More pain, because poor sleep reduces pain tolerance
Yes, your body clock affects your pain levels — and the psychological experience of the pain.
A Surprising Warning: You Can Use Bright Light Too Early
One thing Dr. Lack shared that really surprised me is that using bright light too early can actually make your sleep timing worse. Your body has a natural “morning window” when light helps you wake up earlier. But if you use bright light before that window opens, it can have the opposite effect.
If you've ever found it hard to fall asleep on a day when you’ve had to wake up much earlier than usual, you've seen this effect in action!
Here’s a simple guideline:
Bright light works best during your 'biological morning' — roughly the two hours before your natural wake time. Using it earlier can make it harder to fall asleep that night.
For example: if your body naturally wakes around 10:00 AM, bright light between 8:00–10:00 AM will help shift your rhythm earlier.
But light before 8:00 AM — when your brain still thinks it’s ‘night’ — can actually push your body clock later, making it harder to fall asleep again that night.
So take a moment to figure out your own ‘earliest safe time’ for bright light — usually around two hours before your natural wake time — so you can shift your sleep gently and avoid accidentally making things harder.
How Circadian Rhythm Affects Fibromyalgia Sleep
Because your circadian rhythm (body clock) helps regulate sleep depth, alertness, temperature, and pain sensitivity, even small disruptions can have a bigger impact when you’re living with fibromyalgia. When your body clock is out of sync, sleep becomes lighter and less restorative — and that ripple effect can make fibro symptoms feel more intense.
When the circadian system drifts off track, the parts of your brain involved in pain processing can become more reactive. This often shows up as higher pain levels, morning stiffness, non-restorative sleep, or feeling “wired and tired” at night.
Your body is simply less resilient when its internal timing is out of rhythm.
Two hormones that rely heavily on circadian timing — melatonin and cortisol — play important roles in this process.
Melatonin helps regulate both sleep and pain. It not only signals your body that it’s time to rest, but it also has anti-inflammatory and pain-modulating effects. When your circadian rhythm is off, your melatonin release becomes irregular or “choppy,” which can lead to frequent awakenings and lighter sleep. Some studies even suggest that people with fibromyalgia may have lower nighttime melatonin levels, which may contribute to increased pain and sleep disruption.
Cortisol is another hormone deeply tied to fibromyalgia symptoms. It should rise in the morning to help you wake up, regulate inflammation during the day, and then taper off at night so your body can rest. In fibromyalgia, cortisol often falls out of its natural rhythm — spiking at the wrong times, staying elevated, or dropping too low. Any of these patterns can increase pain sensitivity, worsen fatigue, and make symptoms harder to manage.
When your circadian rhythm is disrupted, your brain may send mixed or mistimed signals about when to release cortisol. Instead of the steady morning rise and gentle evening decline, levels may surge late in the day, dip when you need energy, or fluctuate unpredictably. This instability keeps your system on higher alert, makes inflammation harder to regulate, and amplifies pain.
Why Fibromyalgia Makes This Even Harder
People with fibromyalgia often have:
- lighter sleep
- more awakenings
- disrupted and reduced deep sleep
- delayed or irregular circadian rhythms
This means your system is already more sensitive. Add cloudy winter mornings, time changes, travel, or inconsistent sleep — and your whole rhythm can easily get knocked off track.
If you’ve ever wondered why you flare right after daylight savings, this is why. Your body clock suddenly misaligns with the world around you.
For many fibro folks, it can feel like jet lag… without ever leaving home.
How Morning Light Can Help Reset Your Rhythm
Professor Lack’s research shows that bright light within the first 1–2 hours after waking is the most powerful way to shift your body clock earlier and stabilize your sleep.
But this is where many of us struggle:
- Winter weather keeps us from experiencing morning sun outdoors
- Cloudy days may not deliver the intensity we need
- We’re indoors getting ready for the day
- Energy levels or pain make mornings difficult in general
That’s where bright-light devices come in.
Why Light Therapy Glasses Are A Game-Changer
In our conversation, Dr. Lack explained how the retimer™ 3 light therapy glasses (affiliate link) were developed after decades of research into the exact wavelengths that shift the body clock. Blue-green light was found to be the most effective for shifting the body clock. Amber and red light, by comparison, had little or no effect.
The retimer™ 3 glasses shine the ideal wavelength of light into your eyes while you go about your morning:
- brushing your teeth
- making breakfast
- enjoying your coffee
- getting ready for the day
They’re also far easier than the old-fashioned light boxes that required sitting still in front of a bright panel.
I use these myself. In fact, they’re one of my 2025 Tami’s Favorite Things! Since I can wear them while I go about my day, I put them on almost immediately when I get out of bed. If I had to sit in front of a light box, that would happen much later, once I'd visited the bathroom, brushed my teeth, loved on Finn, and so on.
They’ve been a huge help not only for shifting my sleep schedule but also for increasing morning alertness and stabilizing my mood.
How to Shift Your Sleep Schedule Safely
Dr. Lack recommends finding your natural rhythm first (the hours when you fall asleep easily on days you don’t set an alarm). From there, you can move your schedule earlier slowly, using bright light at the right time.
Here’s the simple version:
- Identify your ideal sleep window
(e.g., you naturally sleep 2:00 AM–10:00 AM) - Wake up 15–30 minutes earlier each day
Small steps work better than big jumps. - Use bright morning light
Aim for 30+ minutes within the first 1–2 hours of waking — but even 5 minutes helps! - Repeat for several days
It may take a week or more to shift 1–2 hours earlier.
Night owls (like me!) often need more time. - Keep mornings consistent
Sleeping in on weekends pushes your rhythm later again — causing “social jet lag.”
The goal is not perfection. It’s stability.
Your body clock loves predictability.
Speaking for myself, I've found that the amount of deep sleep I get (according to my Apple Watch) almost doubles when I'm consistent with my sleep and wake times. When I first started working on my deep sleep, I was averaging 39 minutes of deep sleep. (This should be closer to 90 minutes, or 10-15% of your total sleep time.) When my sleep schedule is stable, I've seen that jump to an hour or more.
What About Night Owls? What About Early Birds?
Some people naturally run late (evening types) while others naturally run early (morning types). Genetics play a big role.
For evening types, morning light is especially helpful because their clocks drift later more easily.
For early types, evening light can help delay the rhythm if they’re waking up too early.
(This is the opposite of what most fibro folks need, but useful knowledge!)
What If You Live Somewhere Dark, Cloudy, or Wintery?
While bright morning sunlight outdoors is the best medicine, it's not always possible.
If you live somewhere farther north (or south, I suppose!), like I do in Seattle, you might not get enough natural morning light to reset your rhythm. When I moved from Portland to Seattle (three hours farther north), I noticed my depression got a bit worse. My doctor had me increase my vitamin D and told me, "We really are the vampire state up here!" (If you remember the movie, Twilight — those vampires lived just a couple hours west of me!)
Cloudy morning light may be too dim to make a difference — and if it's cold and rainy, we're not going to want to go outside.
In those cases, Dr. Lack recommends bright-light therapy glasses or indoor bright-light sources. Light therapy glasses, such as the retimer 3 glasses, offer the benefit of mobility over cumbersome light boxes. And the easier they are to use, the more likely you will actually USE them!
Can Fixing Your Body Clock Improve Fibromyalgia Symptoms?
Indirectly? Absolutely.
When your sleep improves, even by a little:
- your pain tolerance increases
- brain fog decreases
- mood stabilizes
- energy improves
- flares become less frequent or less intense
In fact, Dr. Maikin proposed in 1975 that fibromyalgia be considered a disorder of non-restorative sleep. Sleep research has also shown that when healthy subjects are kept from getting into deep sleep, they develop fibromyalgia-like symptoms of pain, fatigue, and brain fog.
Good sleep isn’t the whole solution — but it’s a powerful foundation.
Key Takeaways
- Your circadian rhythm is your body’s internal clock — and it's easily thrown off.
- Light, especially morning light, is the strongest signal for keeping that clock on track.
- People with Fibromyalgia are more sensitive to circadian disruption.
- Light therapy glasses can help when natural morning light is limited.
- Shifting your sleep schedule requires gentle, consistent steps — not abrupt changes.
- It's crucial to know your natural sleep schedule before trying to shift it earlier or later.
- Using bright light too early can push your body clock later.
- Trying to get up or use light therapy too early shifts your body clock later, not earlier.
Looking for More Help With Sleep?
Here are some helpful Fibromyalgia Podcast® episodes:
- Episode 173: Fibromyalgia, Sleep, and Your Body Clock with Dr. Leon Lack
- Episode 95: Sleep Better with Sovann Pen
- Episode 96: Fibromyalgia Sleep
If you’d like to explore the retimer™ 3 light therapy glasses, you’ll find them in Tami’s Favorite Things for 2025.
Action Steps
Ways to Support Your Body Clock Today
- Figure out your “earliest safe time” for bright light.
This is usually about two hours before your natural wake time, and knowing it helps you shift your sleep gently without accidentally making things harder. - Get morning light within 1–2 hours of waking.
Natural daylight is ideal, but if mornings are dark or cloudy where you live, use a bright-light therapy device such as the retimer™ 3 glasses (get Tami's Favorite Things 2025 here). The instructions that came with my retimer light therapy glasses recommends 45 minutes — but anything is better than nothing! - Keep your wake-up time consistent.
Your body clock loves stability. Try to go to bed and wake up around the same time every day — even on weekends — to avoid “social jet lag.” - Avoid sleeping in to “catch up.”
If you have fibro, you may want to sleep in due to still feeling exhausted. This shifts your body clock even later, making it harder to fall asleep the next night. Instead, aim for an early, gentle wind-down each evening, and bright light in the morning to anchor your clock. - Track your natural rhythm.
Notice when you fall asleep easily and when you wake up without an alarm. This helps you understand your body’s preferred schedule so you can shift it slowly. - Make small shifts, not big jumps.
If you want to move your sleep earlier, adjust your wake time by just 15–30 minutes every few days (or more!). Pair each change with bright morning light. - Reduce bright evening light — unless you're trying to shift your body clock later.
The use of bright evening light will shift the body clock to a later bedtime. Unless that is your intention, dim overhead lights, use warm bulbs, and limit screens 1–2 hours before bed. - Support your evenings with calming habits.
Try gentle stretching, a warm bath, deep breathing, or a soothing audiobook to signal “sleep mode.” This also helps to calm the overactive "fight-or-flight" response we have with fibromyalgia. - Pay attention to flares after time changes.
If you notice symptoms worsening after daylight savings or seasonal shifts, your body clock may be struggling to keep up — and light exposure can help. Make note of this and use what you learn to prepare ahead of time for the next time change. - Ask for support.
If body clock issues are severely affecting your life, working with someone, such as a sleep specialist or Certified Fibromyalgia Coach®, can help you troubleshoot next steps.
Even small steps to reset your body clock can improve fibromyalgia sleep issues and help your morning energy.
Ready to feel better?
You don’t have to walk this path alone. Schedule your consultation with me or one of my students or coaches today, and discover how having someone who truly understands fibromyalgia can make all the difference.
Photos courtesy of Tami Stackelhouse. Cover image by Ake Ngiamsanguan/iStock. Bedside table photo by Benjamin Voros. Used with permission.
About Tami Stackelhouse
Tami Stackelhouse is an award-winning author, founder of the International Fibromyalgia Coaching Institute (IFCI), and one of the most influential voices in fibromyalgia today, having helped hundreds of thousands of people worldwide rethink what is possible with fibromyalgia. Through her signature Fibromyalgia Wellness Framework℠, Tami is helping transform the way fibromyalgia is understood, supported, and lived — moving people beyond symptom management and into a future they once believed was out of reach.
Photo by Emily Broadbent
