Why Can’t I Sleep? 7 Science-Backed Causes & Solutions
- Murdo Duguid
- Jul 2
- 4 min read
Why Can’t I Sleep? 7 Science-Backed Causes & Solutions
Struggling to sleep through the night or nod off in the first place? You’re not alone. In fact, “Why can’t I sleep?” is one of the most Googled health questions each year. The answer isn't always simple, but it is understandable. Sleep is regulated by a tightly linked network of hormonal, neurological, and behavioural signals, and when just one part of that system is off, it can throw everything else into chaos.
In this article, we’ll explore seven of the most common causes of poor sleep and the science-backed strategies to overcome them. From cortisol surges at 3 a.m. to overlooked links between gut health and insomnia, we’ll break it all down in a clear, actionable way.
1. Stress & Cortisol: Is Stress the Reason You Wake Up at 3 A.M.?
One of the most common causes of night-time wakefulness is elevated cortisol. Cortisol, your primary stress hormone, follows a diurnal pattern: it should be low at night and rise in the early morning. But when you're chronically stressed, this rhythm can shift.
If you're waking up in the early hours with a racing mind or shallow breathing, chances are your cortisol levels are spiking too early. This is often a sign of poor stress resilience or an overactive HPA (hypothalamic-pituitary-adrenal) axis.
Solution: Stress reduction strategies like breathwork, guided meditation, and even journaling before bed have been shown to reduce cortisol. Supplement-wise, magnesium and adaptogens like ashwagandha or bacopa may also help restore HPA axis balance over time. You can find both magnesium and ashwagandha in our Overnight Balance formula.
2. Blue Light & Melatonin: Is Screen Time Sabotaging Your Sleep?
Melatonin is your brain’s natural signal that it’s time to sleep. Unfortunately, blue light, emitted by phones, laptops, and LED lighting, can suppress melatonin production by confusing the brain into thinking it’s still daytime.
This delay in melatonin secretion pushes your circadian rhythm forward, making it harder to fall asleep when you want to.
Solution: Use blue light blocking glasses after sunset, switch your screens to “night mode”, and aim to avoid screen exposure at least one hour before bed. Natural support like magnesium and chamomile can also complement this behavioural shift. Learn more about our sleep support supplements here.
3. Magnesium Deficiency: Does Magnesium Help You Sleep?
Magnesium is involved in over 300 biochemical reactions in the body, including those that regulate muscle relaxation and the production of calming neurotransmitters like GABA.
Magnesium deficiency has been linked to insomnia, anxiety, and even restless leg syndrome, a condition that can severely disrupt sleep. Among the various forms, magnesium glycinate is especially favoured for its calming effects.
Solution: Supplementing with 200–400mg of magnesium glycinate, or other forms, 1–2 hours before bed may help improve sleep latency and depth. Pair it with a consistent wind-down routine for maximum effect. Our Overnight Balance supplement contains this sleep-supporting mineral.
4. Gut Health: Can Digestive Issues Affect Sleep Quality?
Your gut isn’t just for digestion—it’s a major player in hormone regulation, inflammation, and even mood. The gut microbiome helps produce serotonin, the precursor to melatonin. A disrupted microbiome (from poor diet, stress, or antibiotics) can interfere with this conversion.
Bloating, acid reflux, and other GI symptoms can also make it physically uncomfortable to fall asleep or stay asleep.
Solution: Increase prebiotic fibre, fermented foods, and consider a targeted probiotic. Avoid heavy meals close to bedtime and support digestion with calming teas like ginger or peppermint.
5. Sleep Hygiene: Are Your Habits Making Things Worse?
Sleep hygiene refers to the habits and environmental factors that influence sleep. This includes bedtime routines, room setup, light exposure, and even what you eat or drink before bed.
Caffeine too late in the day, alcohol in the evening, or even an irregular sleep schedule can throw off your natural rhythm.
Solution: Set a regular sleep-wake schedule, create a dark and quiet environment, avoid caffeine after 2pm, and replace evening alcohol with non-stimulating alternatives like tart cherry juice.
6. Hormonal Disruptions: Is Your Body Clock Out of Sync?
Melatonin isn’t the only hormone at play. Cortisol, oestrogen, progesterone, and thyroid hormones can all impact your sleep-wake cycle. Women often report poor sleep around their menstrual cycle or during perimenopause due to fluctuations in oestrogen and progesterone.
Similarly, underactive thyroid function can lead to fatigue during the day and restlessness at night.
Solution: Track your hormonal cycle and consider speaking to a practitioner about testing. Supplementing with magnesium, B6, or adaptogens may support hormonal regulation and improve sleep patterns over time.
7. The Wrong Sleep Environment: Is Your Bedroom Helping or Hindering?
The ideal sleep environment is dark, cool (around 18°C or 65°F), quiet, and comfortable. If your bedroom is too warm, noisy, or filled with disruptive lighting, even the best supplements and habits won’t help.
Solution: Use blackout curtains, invest in good bedding, consider white noise machines, and drop the temperature by a few degrees. Aromatherapy (like lavender essential oil) can also signal your brain that it’s time to wind down.
FAQs
Q: How long before bed should I take magnesium?
A: Magnesium is best taken 1–2 hours before bed to align with your natural wind-down phase.
Q: What is the best temperature for sleep?
A: Between 16–18°C (60–65°F) is generally optimal for deep, uninterrupted sleep.
Q: Can stress really cause me to wake up at 3 a.m.?
A: Yes, a cortisol spike triggered by stress can disrupt your sleep around that time due to your body's natural hormonal rhythm.
Q: What’s the best supplement for sleep?
A: Magnesium is widely supported by evidence. Ashwagandha and theanine can also help, especially when combined in targeted blends like Overnight Balance.
Q: Can digestive problems really cause insomnia?
A: Absolutely. The gut and brain are closely linked, and disruptions in gut health can influence sleep hormones like serotonin and melatonin.
Final Thoughts: Stack Solutions, Don’t Rely on Just One
Often, there isn't just one reason why you can't sleep, it's a combination of several low-grade imbalances. By addressing stress, nutrition, environment, and rhythm together, you create the conditions your body needs to restore deep, refreshing rest.
And remember, while supplements like magnesium glycinate or herbal formulas like Moderaci’s Overnight Balance can be powerful tools, they work best when paired with strong foundational habits.
Sleep isn't something you chase, it's something you set yourself up to receive.
Written by Murdo Duguid, BSc Biochemistry & Level 3 Personal Trainer
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