Why You're Exhausted All Day But Can't Sleep at Night, the Cortisol Curve Explained
If you're dragging through your afternoon meetings but wide awake at 11 PM, your cortisol curve is probably upside down.
You know the feeling. Your alarm goes off, and you can barely pry your eyes open. You need three coffees just to function through the morning. By 3 PM, you're fantasising about crawling under your desk for a nap. But then, the moment your head hits the pillow at night? Your mind races. Your body feels wired. Sleep feels impossible.
This isn't just bad luck or poor sleep hygiene. It's your cortisol curve—and when it's disrupted, it doesn't just steal your sleep. It accelerates ageing at the cellular level.
After 20+ years in healthcare, including extensive NHS experience, and as a certified health coach specialising in stress and longevity, I've seen this pattern destroy the health of countless high-achieving professionals. The good news? Once you understand what's happening, you can fix it.
The Natural Cortisol Curve: How It's Supposed to Work
Cortisol is often called the "stress hormone," but that's only part of the story. Yes, it rises when you're under pressure, but cortisol also follows a natural daily rhythm that's essential for energy, focus, and restorative sleep.
In a healthy cortisol curve:
Morning (6-9 AM): Cortisol peaks within 30-45 minutes of waking. This is called the Cortisol Awakening Response (CAR).[1] It's what gives you natural energy to start your day, sharpens your focus, and gets your metabolism moving.
Midday (12-3 PM): Cortisol gradually declines but remains elevated enough to sustain energy and cognitive function through your workday.
Evening (6-9 PM): Cortisol drops significantly, signalling to your body that it's time to wind down. This allows melatonin (your sleep hormone) to rise.
Night (10 PM-2 AM): Cortisol reaches its lowest point, allowing deep, restorative sleep. During this time, your body repairs tissues, consolidates memories, and performs critical anti-ageing processes.
This rhythm isn't arbitrary. It's hardwired into your circadian biology and synchronised with light exposure, meal timing, and physical activity.[2] When this curve is intact, you wake up refreshed, maintain steady energy, and fall asleep easily.
What Happens When Your Cortisol Curve Gets Disrupted
Chronic stress, the kind that comes from demanding careers, constant connectivity, poor boundaries, and relentless pressure, can disrupt this natural rhythm.
In a disrupted cortisol curve:
Morning: Cortisol response is blunted or low. You wake up exhausted, foggy, and dependent on caffeine.
Midday: Cortisol may spike erratically in response to stressors (emails, deadlines, conflicts), causing anxiety and irritability.
Evening: Instead of dropping, cortisol remains elevated. You feel "tired but wired."
Night: Elevated cortisol interferes with melatonin production. Your mind races, your body stays alert, and sleep becomes elusive.
This isn't just about feeling tired. A flattened cortisol curve, in which the normal peak-to-trough pattern is reduced, has been associated with various health concerns in the research literature.[3]
Why This Causes Exhaustion AND Insomnia
It seems paradoxical: How can you be exhausted all day but unable to sleep at night?
The answer lies in cortisol's dual role.
Exhaustion during the day happens because your morning cortisol, the hormone that's supposed to energise you, is insufficient. When the natural cortisol awakening response is blunted, you lack that biological boost to start your day. Without it, you rely on external stimulants (caffeine, sugar) that create energy crashes later.
Insomnia at night happens because your evening cortisol, which should be low, remains elevated. This keeps your nervous system in a heightened state of alertness. Your heart rate stays elevated, your mind stays active, and melatonin production is suppressed.[4] Even if you're physically exhausted, your body won't shift into sleep mode.
The result? You're stuck in a vicious cycle: poor sleep increases stress response, which further disrupts cortisol patterns, which worsens sleep quality.
The Stress-Sleep-Aging Connection
Here's where this gets serious.
When your cortisol patterns are chronically disrupted, it can trigger a cascade of biological changes:
1. Increased inflammation: Chronic stress and disrupted cortisol patterns have been linked to elevated inflammatory markers.[5] Chronic inflammation is a key driver of accelerated ageing.
2. Impaired cellular repair: Deep sleep is when your body activates important repair processes, including autophagy (cellular cleanup) and growth hormone release for tissue repair.[6] Without adequate deep sleep, these restorative processes are compromised.
3. Cellular ageing markers: Research has shown associations between chronic stress, poor sleep quality, and accelerated cellular ageing.[7]
4. Metabolic changes: Disrupted cortisol patterns can affect insulin sensitivity and glucose metabolism, potentially contributing to weight gain (especially around the midsection) and metabolic concerns.[8]
5. Cognitive function: Poor sleep quality impairs memory consolidation and cognitive performance. Chronic sleep deprivation has been associated with increased risk of cognitive decline.[9]
In my two decades working in healthcare, I've witnessed how this cycle manifests: professionals in their 40s looking and feeling a decade older, struggling with weight, brain fog, and chronic fatigue, often rooted in stress-induced sleep disruption.
5 Science-Backed Strategies to Restore Your Cortisol Rhythm
The good news? Your cortisol rhythm is responsive to lifestyle interventions. With targeted strategies, you can work to restore its natural pattern and reclaim your energy and sleep.
1. Morning Light Exposure
Why it works: Bright light exposure in the morning helps reset your circadian clock and supports a healthy cortisol awakening response.
How to do it: Get outside for 10-20 minutes of natural daylight within 30-60 minutes of waking (even on cloudy days). If that's not possible, consider a 10,000-lux light therapy box. Avoid wearing sunglasses during this time to allow light to reach your eyes.
The science: Light exposure in the morning has been shown to influence circadian rhythms, cortisol patterns, and evening melatonin production.[10]
2. Strategic Evening Routine
Why it works: Creating a consistent wind-down routine helps signal to your body that it's time to lower cortisol and prepare for sleep.
How to do it:
Dim lights 2-3 hours before bed (use warm, amber lighting)
Reduce screen exposure or use blue-light blocking glasses in the evening
Practice a calming ritual: gentle stretching, journaling, or reading
Keep your bedroom cool (18-20°C)
The science: Blue light exposure in the evening can suppress melatonin production and interfere with natural sleep-wake cycles.[11] Creating consistent pre-sleep routines supports better sleep quality.
3. Meal Timing and Blood Sugar Balance
Why it works: Blood sugar fluctuations can trigger cortisol responses. Eating at consistent times and balancing macronutrients helps stabilise cortisol throughout the day.
How to do it:
Eat breakfast within 1-2 hours of waking (include protein and healthy fats)
Avoid high-sugar, high-refined-carb meals that cause blood sugar spikes and crashes
Maintain regular meal timing (avoid going more than 4-5 hours without eating)
Finish dinner 2-3 hours before bed
The science: Research indicates that meal timing and composition can influence cortisol rhythms and metabolic function.[12]
4. Natural Supplements for Cortisol Support
Why it works: Nature provides powerful allies for restoring balance to an overworked nervous system. These evidence-based botanicals and nutrients work with your body's innate healing capacity to regulate stress response and support restorative sleep gently.
The key is timing: certain supplements help boost your morning energy, while others help calm your evening cortisol to prepare you for deep sleep.
Morning & Daytime Support (to restore healthy cortisol awakening):
Rhodiola rosea (170-185mg of standardised extract, typically taken twice daily): This Arctic adaptogen has been used in traditional Scandinavian and Russian medicine for centuries to combat fatigue. Research in physicians working night shifts showed that a standardised rhodiola extract improved mental performance and reduced fatigue during periods of stress-induced exhaustion.[13] In traditional use, rhodiola tea is valued for helping the body maintain resilience during demanding periods.
Ashwagandha (300mg twice daily of high-concentration extract): Used for thousands of years in Ayurvedic medicine, this adaptogenic root has been studied for its effects on stress and anxiety. A well-designed clinical trial found that adults taking ashwagandha extract experienced significant reductions in stress scores and serum cortisol levels compared to placebo, along with improvements in overall well-being.[14] This suggests ashwagandha may help the body adapt to chronic stress rather than simply masking symptoms.
Evening & Sleep Support:
Magnesium glycinate (250-500mg): Magnesium is involved in hundreds of enzymatic processes, including those that support nervous system function and muscle relaxation. This highly absorbable form is particularly gentle on digestion. A clinical trial in elderly adults with primary insomnia found that magnesium supplementation improved subjective measures of sleep quality, sleep time, and early morning awakening.[15] Many people have suboptimal magnesium intake, and stress can further deplete stores. Take 1-2 hours before bed.
L-theanine (200mg): This amino acid is naturally found in green tea and has been studied for its calming properties. Research shows L-theanine can reduce both psychological and physiological stress responses without causing drowsiness.[16] It's thought to work by influencing neurotransmitter activity in the brain, promoting a state of relaxed alertness. This makes it particularly useful for evening use when you want to calm racing thoughts without sedation.
Phosphatidylserine (300-800mg): This phospholipid is a natural component of cell membranes, particularly abundant in brain tissue. Studies have shown that phosphatidylserine supplementation can help moderate the cortisol response to physical stress.[17] While most research has focused on exercise-induced cortisol elevation, this suggests potential for supporting a more balanced stress response overall. May be taken in divided doses or in the evening.
Chamomile (1-2 cups of tea, or 400-1,600mg extract): This gentle herb has been used across cultures for centuries as a natural sleep aid and calming agent. Chamomile contains apigenin and other compounds that interact with brain receptors associated with relaxation and sleep initiation.[18] A warm cup of chamomile tea 60 minutes before bed can become a soothing ritual that signals your nervous system it's time to wind down.
Important: These are therapeutic tools that work best as part of a comprehensive approach, including the lifestyle strategies outlined above. Quality matters; look for third-party tested supplements from reputable sources (look for certifications like USP, NSF, or ConsumerLab). Always work with a qualified healthcare professional to create a personalised protocol, determine appropriate dosing for your individual needs, and ensure supplements don't interact with any medications or existing health conditions. Individual responses vary, and what works for one person may not work for another.
5. Stress Management Practices
Why it works: Chronic psychological stress is a primary driver of cortisol dysregulation. Daily stress management practices can help retrain your nervous system response.
How to do it:
Breathwork: 5-10 minutes of slow, diaphragmatic breathing (try the 4-7-8 technique: inhale for 4, hold for 7, exhale for 8)
Meditation or mindfulness: Even 10 minutes daily can support stress management
Movement: Regular moderate exercise (avoid intense workouts late in the day)
Boundaries: Protect your evening hours from work emails and stressful conversations
The science: Multiple studies have demonstrated that mindfulness-based practices, breathwork, and meditation can reduce perceived stress and support healthy cortisol patterns.[17]
Your Cortisol Curve Is Responsive
If you're exhausted all day but can't sleep at night, you're not broken. Your body is responding to chronic stress by staying alert when you should be resting.
But here's what I know from 20+ years in healthcare and my specialised training in health coaching: when you address the root cause, chronic stress and cortisol dysregulation, meaningful changes are possible. Energy can return. Sleep can deepen. Mental clarity can improve. And the accelerated ageing process can slow down.
You don't have to accept exhaustion and insomnia as your new normal.
Ready to restore your energy and sleep? Book a free discovery call and let's create a personalised plan to support your cortisol rhythm and reclaim your vitality. 💛
References
[1] Fries E, Dettenborn L, Kirschbaum C. The cortisol awakening response (CAR): facts and future directions. Int J Psychophysiol. 2009;72(1):67-73.
[2] Clow A, Hucklebridge F, Stalder T, Evans P, Thorn L. The cortisol awakening response: more than a measure of HPA axis function. Neurosci Biobehav Rev. 2010;35(1):97-103.
[3] Adam EK, Quinn ME, Tavernier R, et al. Diurnal cortisol slopes and mental and physical health outcomes: A systematic review and meta-analysis. Psychoneuroendocrinology. 2017;83:25-41.
[4] Steiger A. Sleep and the hypothalamo-pituitary-adrenocortical system. Sleep Med Rev. 2002;6(2):125-138.
[5] Raison CL, Miller AH. When not enough is too much: the role of insufficient glucocorticoid signaling in the pathophysiology of stress-related disorders. Am J Psychiatry. 2003;160(9):1554-1565.
[6] Besedovsky L, Lange T, Born J. Sleep and immune function. Pflugers Arch. 2012;463(1):121-137.
[7] Epel ES, Blackburn EH, Lin J, et al. Accelerated telomere shortening in response to life stress. Proc Natl Acad Sci U S A. 2004;101(49):17312-17315.
[8] Champaneri S, Xu X, Carnethon MR, et al. Diurnal salivary cortisol is associated with body mass index and waist circumference: the Multiethnic Study of Atherosclerosis. Obesity (Silver Spring). 2013;21(1):E56-E63.
[9] Yaffe K, Falvey CM, Hoang T. Connections between sleep and cognition in older adults. Lancet Neurol. 2014;13(10):1017-1028.
[10] Leproult R, Colecchia EF, L'Hermite-Balériaux M, Van Cauter E. Transition from dim to bright light in the morning induces an immediate elevation of cortisol levels. J Clin Endocrinol Metab. 2001;86(1):151-157.
[11] Chang AM, Aeschbach D, Duffy JF, Czeisler CA. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proc Natl Acad Sci U S A. 2015;112(4):1232-1237.
[12] Qian J, Scheer FAJL. Circadian System and Glucose Metabolism: Implications for Physiology and Disease. Trends Endocrinol Metab. 2016;27(5):282-293.
[13] Abbasi B, Kimiagar M, Sadeghniiat K, et al. The effect of magnesium supplementation on primary insomnia in elderly: A double-blind placebo-controlled clinical trial. J Res Med Sci. 2012;17(12):1161-1169.
[14] Chandrasekhar K, Kapoor J, Anishetty S. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults. Indian J Psychol Med. 2012;34(3):255-262.
[15] Kimura K, Ozeki M, Juneja LR, Ohira H. L-Theanine reduces psychological and physiological stress responses. Biol Psychol. 2007;74(1):39-45.
[16] Monteleone P, Beinat L, Tanzillo C, et al. Effects of phosphatidylserine on the neuroendocrine response to physical stress in humans. Neuroendocrinology. 1990;52(3):243-248.
[17] Pascoe MC, Thompson DR, Ski CF. Yoga, mindfulness-based stress reduction and stress-related physiological measures: A meta-analysis. Psychoneuroendocrinology. 2017;86:152-168.
This content is for educational purposes only and is not intended as medical advice. Always consult with a qualified healthcare professional before making changes to your health routine or starting new supplements.