Circadian Rhythms, Hormones, and Sleep

Wes Morgan
Apr 24
3 min read

The Overlooked Key to Mental and Metabolic Health

Ever feel completely wrecked after a bad night’s sleep, even if you’ve eaten well and trained hard? That’s your circadian rhythm flipping you the bird. You can eat the cleanest diet and hit the gym daily, but if your sleep is garbage, your hormones and mental health will suffer.

Your circadian rhythm is your internal 24-hour clock that regulates your

sleep-wake cycle
hormone release
appetite
digestion
body temperature
and even your mood.

This internal clock is synced primarily by light and timing of food intake, and it influences some of the most critical hormones in your body.

How certain hormones effect you circadian Rhythm.

Melatonin (Sleep hormone)
- Rises when it gets dark, promoting sleep.
  
  Suppressed by blue light from screens and LED lighting at night.
- If melatonin is disrupted, sleep onset is delayed, and quality is reduced.
- Poor melatonin = reduced deep sleep = reduced recovery and hormone balance.
- Fix = turn bluelight filter ON on devices, wear bluelight filter glasses
  Amazon.com.au : blue light glasses
  The darker the lens the better for night. The clearer ones are protective when staring at computers all day.
Cortisol (Stress hormone)
- Naturally peaks in the morning to wake you up (cortisol awakening response) and should drop in the evening.
- Chronic stress or late-night light exposure can keep cortisol elevated at night, disrupting sleep, impairing recovery, and increasing cravings the next day.
- Elevated cortisol interferes with insulin sensitivity and can contribute to fat storage, especially around the belly.
Insulin and Glucagon (Blood sugar regulation)
- Circadian biology shows insulin sensitivity is highest in the morning and lowest at night. That’s why we have a low carb breakfast!
- Very late-night eating = higher blood glucose levels = more fat storage and higher inflammation. Best to eat carbs between 10amto 6pm
Estrogen and Testosterone
- Both are influenced by sleep quality and circadian timing.
- Testosterone peaks in the early morning; disrupted sleep reduces its production. Morning erection is directly correlated to testosterone levels. No morning wood = low test
- Estrogen rhythms are essential for mood regulation and sleep; disruption can worsen PMS, mood swings, and mental health in women.

Why This Matters for Weight Loss & Mental Health

Sleep less than 7 hours?

Poor sleep increases ghrelin (hunger hormone) and decreases leptin (satiety hormone). This makes you hungrier and less likely to feel full.
You crave high-fat, high-sugar foods the next day. This isn't just lack of willpower—it's your biology.
Sleep deprivation impairs the prefrontal cortex, the area responsible for decision-making. This leads to worse food choices and missed workouts.

🧠 “Your brain craves junk food when you’re sleep-deprived. You can’t outsmart it,”

How to Fix Your Rhythm (Without Quitting Modern Life)

Get AM sunlight daily (within 30 mins of waking)
- Signals to your brain it's time to be awake
- Suppresses melatonin and boosts serotonin = better mood and better sleep later
- Needs to hit the eyes directly, not through windows or sunglasses
- Grounding: Walk/stand barefoot on the earth.
Cut artificial light exposure at night
- Blue light from screens suppresses melatonin. Use blue light blockers after sunset.
- Reduce overhead LEDs; consider warm, dim lamps in the evening
Set a consistent sleep-wake cycle
- Go to bed and wake up at the same time—even on weekends
- Your body thrives on predictability
Avoid late-night eating
- Finish your last meal at least 2 hours before bed
- Your gut has its own circadian rhythm and needs time to rest and repair
Exercise in the morning or early afternoon
- Movement helps anchor your circadian rhythm
- Evening workouts are OK but avoid intense training close to bedtime