Welcome to Sun & Soil
Here's how to use it:
- Today: what to do right now, your UV index, your skin type and sun-session timer, your daily checklist, and a mood check-in. Allow location access when your phone asks, so the UV index matches where you are.
- Philosophy: my four pillars of health and a metabolic health checker.
- Grocery: pull this up at the store and tap foods to build your list.
- Move: your weekly walking and strength plan.
- Light: how sunlight and darkness shape your health.
- About: my story, a day in my life, and how to reach me.
Everything you enter stays on this device.
Get outside and let the sun set your clock.
The first bright light of the day tells every cell in your body what time it is.
Example: Chicago is 41.88, -87.63. To find yours, open Google Maps or Apple Maps and press and hold on your location to drop a pin. The latitude and longitude appear with the pin. Use a minus sign for south and west.
Know your skin type: the Fitzpatrick scale
Dermatologists use the Fitzpatrick scale to sort skin into six types by how it reacts to the sun. Your type tells you how fast you burn, so you can get the benefits of sunlight without the damage. Tap the type that matches you.12
Estimates for unprotected skin in clear sky. "Now" uses the UV index for your location above.
How to use it
- Find your type above. If you're between two, choose the lower one.
- Check the UV index above. Below 3 you won't burn or make vitamin D. At 3 and above, your clock starts.
- Aim for about half your time to burn, then cover up or move to shade. That's enough to make vitamin D without damage.
- Build up gradually. Start short in spring and add a few minutes each day. A slowly built tan is your skin's natural protection.
- Never burn. Pink skin means you stayed out too long.
Tap Start when you step into the sun, and Stop when you go inside or cover up.
The timer adds up your sun as the UV index changes, using your skin type and location above. It alerts you when you reach about half your time to burn. It keeps running if you switch tabs.
Today's checklist
Check off each habit as you do it. The list resets at midnight. Your streak counts the days you complete all eight daily habits. Strength days don't count toward it, since you train 2–3 times a week. Saved on this device only.
How did you feel today?
Rate your overall mood and energy after following today's steps, then check in on the wins the scale can't show. Over time, you'll see how the habits affect how you feel.
Tap each one that's true for you today.
At 58 I want to be strong, steady on my feet and sharp. A number between my toes tells me none of that.
MAXINE PYE ↗, who stopped weighing herself five years ago and goes by these questions instead
Saved on this device only. You can change today's answer any time before midnight.
How you're doing on each step
The goal in health is to feel better overall. Improving our health is a process. It's about progress, not perfection. Eating healthy whole foods 90% of the time will definitely move the needle in a very positive direction.
Sunrise and sunset for your location appear here.
No sunglasses or contacts, not through a window. Longer on cloudy days.
Aim for 30–40 g of protein with healthy fats (e.g., butter, eggs, avocado, full-fat raw milk, full-fat Greek yogurt, raw milk kefir).
A walk after lunch blunts the blood-sugar spike and adds daylight.
Low, warm light tells your brain evening is coming.
Finish eating 3–4 hours before bed to improve sleep quality and digestion. Even better, eat only during daylight hours whenever possible.
No LEDs, screens, or tech for 2 hours. Lamps low, warm, and below eye level.
Blackout room around 18 °C / 65 °F. Same wake time every day.
Sources for this page (2)
- Fitzpatrick TB. The validity and practicality of sun-reactive skin types I through VI. Archives of Dermatology. 1988;124(6):869–871. View source ↗
- World Health Organization. Global Solar UV Index: A Practical Guide. Geneva: WHO; 2002. View source ↗
The Foundation & Pillars of Health
Your body has an amazing ability to heal and improve its metabolism when it's given the right environment. Your genes load the dice, but your environment decides how they're expressed: what you eat, how you move, think, sleep, and breathe, your relationships, your stress, and your toxin exposure.
Donnie Lacy
Certified Functional Nutritional Therapy PractitionerCertified by the Nutritional Therapy Association (NTA)
I've been a Type 1 diabetic for 36 years, and I was overweight and unhealthy for most of my adult life. I used to be 90 pounds heavier than I am now. After suffering a TIA in 2022 and watching friends and family suffer from chronic disease, I decided it was finally time to become harder to kill.
Your body isn't broken. Your environment is.BEN FUNG
We are sick and getting sicker
The five markers of metabolic health
Cardiac surgeon Dr. Philip Ovadia uses the five standard clinical markers.78 If all five are in range without medication for them, you're metabolically healthy, among roughly 12% of U.S. adults.3 Three or more out of range means metabolic syndrome, with a higher risk of type 2 diabetes, heart disease, and other conditions.
Markers Dr. Ovadia also watches
He considers these better signs of underlying metabolic function than LDL cholesterol alone.
- Triglyceride-to-HDL ratio: ideally 1 or lower; under 2 is a sign of good metabolic health. The checker above calculates yours.
- Fasting insulin: ideally under 7 µIU/mL, with normal fasting glucose.
- A1C: in the normal range.
- Non-smoking, especially when evaluating heart disease risk.
How the pillars help
- Cutting seed oils, refined carbs, and sugar lowers triglycerides and fasting glucose.
- Strength training and daily walking shrink the waist and improve insulin sensitivity.
- Morning light, darkness at night, and good sleep improve blood sugar control.
- A calm nervous system helps bring blood pressure down.
Talk with your doctor about your results, especially before changing any medication.
Four pillars on one foundation
Your circadian rhythm is the foundation everything else stands on. Build the four pillars on top of it. Tap a pillar to read about it.
Circadian rhythm
Your circadian rhythm is the roughly 24-hour cycle that regulates sleep, metabolism, and hormone release. Light and dark are its main signals. Disrupt your circadian signaling and growth and metabolism pay a price, called disease.
- Get early morning sunlight to reset your clock9
- Keep the same sleep schedule, even on weekends
- Limit blue light at night
- Time meals with the sun: eat only during daylight hours whenever possible, and finish your last meal 3–4 hours before bed to improve sleep quality and digestion
Relax
The true measure of success is a calm nervous system. Spend more time in rest-and-digest mode (parasympathetic) and less in fight-or-flight (sympathetic).
- Take an outdoor walk or hike
- Cuddle with your pet for 5–10 minutes
- Practice deep breathing (3-4-5)
- Listen to calming music
- Step away from social media for several hours
- Be in nature and outdoors often
- Spend time grounding to the earth (bare feet touching the ground)10
- Spend time with loving friends and family
Practice gratitude daily. Overwhelmed, stuck, anxious, or stressed? Go outside. Nature is medicine.
Eat
Nutrition is about removing the toxins from your diet and improving the quality of the foods you eat. Every time you eat or drink, you're either feeding disease or fighting it.
- Eat a nutrient-dense, whole-food diet that's bioavailable, meaning your body recognizes, digests, absorbs, and uses it as fuel
- Nutrients are protein, fats, carbohydrates, vitamins, minerals, clean water, and sunlight
- Cut out seed oils, refined grains, and processed sugars and artificial sweeteners
- The closer to the source, the better. Eat locally and seasonally: only eat what grows in your location and region.
- Eat with the sun. Whenever possible, eat only during daylight hours, and finish your last meal 3–4 hours before bed to improve sleep quality and digestion.11
- Eat slowly
- Chew your food to an applesauce consistency
- Turn the TV off and put your phone away when eating
- Don't eat on the go or standing up. Sit down and relax: digestion is a rest-and-relax event.
- Eat as many meals as possible outdoors, weather permitting
- Limit the amount of liquids you drink during meals
See the Grocery tab for the foods I recommend.
Move
Walk more. Aim for 7,000 steps a day. Always take the stairs (ATTS!). Park as far from the door as you can. Walk 150 minutes a week, which is 30 minutes, 5 days a week.
Become stronger. Muscle is the forgotten organ and the organ of longevity. Strength train 2–3 times a week, outdoors in sunlight. Work each muscle group twice a week with one slow, controlled set to failure lasting 45–90 seconds.
See the Move tab for the weekly plan.
Sleep
Sleep is a skill, and great sleep starts with stepping into the sunlight. You're responsible for how much light gets into your eyes each day, and not from behind a window or through sunglasses.
- Keep a consistent sleep schedule, even on weekends
- No LEDs, screens, or tech for 2 hours before bed
- Keep the room cool
- Use blackout curtains or a sleep mask
- Use mouth tape (Hostage brand) for nasal breathing
- Unplug the WiFi router before bedtime
- Put your phone on airplane mode, and don't charge it or sleep near it
- L-Theanine, 400 mg (Horbaach): calms the mind without making you groggy
- Mag ATP (MitoLife): relaxes muscles and the nervous system
- Melatonin, 50 mg (MitoLife): the darkness signal, and a powerful antioxidant
- Glycine, 3 g (Life Extension): lowers core body temperature to help you fall into deep sleep12
- Inositol powder (Nutricost): calms racing thoughts and supports staying asleep
Check with your doctor before starting supplements, especially if you take medication.
Being healthy is an act of rebellion.
A healthy man wants a thousand things, a sick man only wants one.CONFUCIUS
You can no longer live in the modern world and not pay attention to your health. You literally have 100 forces working against you for the first time in human history.GEORGE FERMAN
Let food be thy medicine and medicine be thy food.HIPPOCRATES
You can't fix your health if you can't get the basics right.JAMES DINICOLANTONIO
Sources for this page (10)
- Araújo J, Cai J, Stevens J. Prevalence of optimal metabolic health in American adults: National Health and Nutrition Examination Survey 2009–2016. Metabolic Syndrome and Related Disorders. 2019;17(1):46–52. View source ↗
- Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion. Chronic Diseases in America. View source ↗
- Cooney E. Nearly 1 in 3 teens have prediabetes, CDC finds, in ‘wake-up call.’ STAT. July 9, 2025. Reports CDC National Health and Nutrition Examination Survey (NHANES) estimates: 32.7% of 12- to 17-year-olds had prediabetes in 2023. View source ↗
- Juul F, Parekh N, Martinez-Steele E, Monteiro CA, Chang VW. Ultra-processed food consumption among US adults from 2001 to 2018. American Journal of Clinical Nutrition. 2022;115(1):211–221. View source ↗
- Alberti KGMM, Eckel RH, Grundy SM, et al. Harmonizing the metabolic syndrome. Circulation. 2009;120(16):1640–1645. View source ↗
- Ovadia P. Stay Off My Operating Table: A Heart Surgeon's Metabolic Health Guide to Lose Weight, Prevent Disease, and Feel Your Best Every Day. 2021.
- Wright KP Jr, McHill AW, Birks BR, Griffin BR, Rusterholz T, Chinoy ED. Entrainment of the human circadian clock to the natural light-dark cycle. Current Biology. 2013;23(16):1554–1558. View source ↗
- Chevalier G, Sinatra ST, Oschman JL, Sokal K, Sokal P. Earthing: health implications of reconnecting the human body to the Earth's surface electrons. Journal of Environmental and Public Health. 2012;2012:291541. View source ↗
- Vujović N, Piron MJ, Qian J, et al. Late isocaloric eating increases hunger, decreases energy expenditure, and modifies metabolic pathways in adults with overweight and obesity. Cell Metabolism. 2022;34(10):1486–1498. View source ↗
- Bannai M, Kawai N. New therapeutic strategy for amino acid medicine: glycine improves the quality of sleep. Journal of Pharmacological Sciences. 2012;118(2):145–148. View source ↗
Your grocery list
Pull this up in the store. Tap items to add them to your cart list. Your checks are saved on this device.
Leave on the grocery store shelf
- Seed oils: canola, soybean, corn, grapeseed, cottonseed, safflower, rice bran, and sunflower. Labels also call them "vegetable oil" or "plant oil."
- Margarine and other butter substitutes. Choose real butter or ghee instead.
- Refined grains and white-flour products. Choose 3-ingredient sourdough and sprouted grains instead.
- Processed sugars and artificial sweeteners, including sugary drinks and juice
- Ultra-processed food: emulsifiers, preservatives, dyes, and anything with a long list of ingredients you can't pronounce
- "Low-fat" products that replace fat with sugar
Supplements & health additions
Food, light, movement, and sleep come first. These fill the gaps and make the healthy choice easier.
My top 7 supplements
- Magnesium ATPMagnesium paired with ATP to support cellular energy, sleep, relaxation, and blood sugar control.
- Vitamin K2Directs calcium into your bones and away from your arteries.16
- Melatonin, 50 mgHigh-dose melatonin taken at night. A powerful antioxidant as well as a sleep signal.
- Vitamin CAntioxidant that supports immunity and collagen production.
- Vitamin EFat-soluble antioxidant that protects your cell membranes.
- Lithium OrotateLow-dose lithium, a trace mineral that supports mood, stress resilience, and brain health.
- Zinc CarnosineZinc bound to L-carnosine to support and repair the lining of the stomach and gut.
- Buffalo organ capsules
- The nutrients of liver and other organs, for people who won't eat them.
- Neprinol AFD
- A systemic enzyme blend with nattokinase and serrapeptase, taken on an empty stomach, to support healthy circulation and help the body break down excess fibrin. Check with your doctor first if you take blood thinners.
- Electrolytes & trace minerals
- Especially if you sweat a lot or eat low carb. I recommend Baja Gold Mineral Salt and Sport Drink brand electrolyte powder.
Health additions
- Blue-light-blocking glasses
- Wear them after sunset to protect melatonin when screens and LEDs are unavoidable.
- Incandescent lighting
- Swap LEDs for incandescent bulbs at home. They give off warm, flicker-free light with far less blue than LEDs.
- Red night lights
- Red bulbs for bathrooms and hallways, so getting up at night doesn't reset your clock.
- Mouth tape (Hostage brand)
- Encourages nasal breathing during sleep, which significantly increases the nitric oxide you take in from your sinuses.17
- Water filter
- Clean water is a nutrient. Filter what comes out of the tap.
Talk with your doctor before starting supplements, especially if you take medication or have a health condition.
Sources for this page (5)
- National Institutes of Health, Office of Dietary Supplements. Zinc: Fact Sheet for Health Professionals. View source ↗
- Fahey JW, Zhang Y, Talalay P. Broccoli sprouts: an exceptionally rich source of inducers of enzymes that protect against chemical carcinogens. Proceedings of the National Academy of Sciences. 1997;94(19):10367–10372. View source ↗
- Consumer Reports. How much arsenic is in your rice? 2014. View source ↗
- Geleijnse JM, Vermeer C, Grobbee DE, et al. Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study. Journal of Nutrition. 2004;134(11):3100–3105. View source ↗
- Lundberg JO, Farkas-Szallasi T, Weitzberg E, et al. High nitric oxide production in human paranasal sinuses. Nature Medicine. 1995;1(4):370–373. View source ↗
Walk more. Become stronger.
Aim for 7,000 steps a day and 150 minutes of walking a week. Strength train 2–3 times a week, outdoors in sunlight when you can, to stack movement and light together.
One set to failure
- Squats▶ Goblet squat
- Pull-ups or rows▶ Pull-up▶ One-arm dumbbell row
- Push-ups or chest press▶ Push-up
- Deadlift or hip hinge▶ Dumbbell Romanian deadlift
- Overhead press▶ Standing dumbbell press
- Plank or loaded carry▶ Plank▶ Kettlebell farmer's carry
All of these can be done at home with a pair of adjustable dumbbells or kettlebells. Tap a video to see the technique.
One set per movement. Move slowly and with control, using a weight heavy enough that you reach failure between 45 and 90 seconds. Work each muscle group twice a week. Muscle is the organ of longevity.
Easy aerobic base
- Brisk walk on an incline, easy cycling, rowing, or a slow jog
- Nose breathing is a good governor
- Morning sessions outside double as light exposure
Builds mitochondria and cardiovascular health. This is the foundation, so keep it easy.
One hard session
- Warm up 5 min
- 4 × 4 min hard (can say a few words only), 3 min easy between
- Or 8 × 20 s sprints, 2 min walk between
- Cool down 5 min
Raises VO₂ max, one of the strongest predictors of a long life.18
Walk more
- Aim for 7,000 steps each day
- Always take the stairs (ATTS!)
- Park as far away as possible from your destination
- Walk 150 minutes a week: 30 minutes, 5 days a week
- 10-minute walk after meals
A 2021 study in JAMA Network Open found that adults who took 7,000+ steps a day had a 50–70% lower risk of premature death.19
Sources for this page (2)
- Mandsager K, Harb S, Cremer P, Phelan D, Nissen SE, Jaber W. Association of cardiorespiratory fitness with long-term mortality among adults undergoing exercise treadmill testing. JAMA Network Open. 2018;1(6):e183605. View source ↗
- Paluch AE, Gabriel KP, Fulton JE, et al. Steps per day and all-cause mortality in middle-aged adults in the Coronary Artery Risk Development in Young Adults study. JAMA Network Open. 2021;4(9):e2124516. View source ↗
Hi, I'm Donnie.
I built Sun & Soil to share what changed my health, in a form you can pull up anywhere: at the grocery store, on a morning walk, or before bed.
Donnie Lacy
Certified Functional Nutritional Therapy PractitionerCertified by the Nutritional Therapy Association (NTA)
- 36 years
I've lived with Type 1 diabetes for 36 years.
- Most of my adult life
I was overweight and unhealthy, about 90 pounds heavier than I am today.
- 2022
I suffered a TIA, a "mini-stroke." Between that and watching friends and family suffer from chronic disease, I decided it was finally time to become harder to kill.
- Today
I'm 90 pounds lighter and a Certified Functional Nutritional Therapy Practitioner, certified by the NTA. This app is the foundation and four pillars I live by.
A day in my life
Here's what the foundation and four pillars look like in my own day. Take what works for you and leave the rest.
Light, grounding, and a real breakfast
- 5:30 AM (around 6 on weekends)
I wake up and take my nattokinase on an empty stomach with some mineral water, then shower. Until the sun comes up, we keep our indoor lights dim, using incandescent bulbs only.
- Breakfast
Usually eggs, cheese, sausage, and sourdough. If I'm short on time, I'll just drink raw milk kefir.
- Supplements
Once I've eaten something, I take vitamin E, vitamin C, lithium orotate, black seed oil (2 capsules), buffalo organ capsules (3), boron glycinate, and L-theanine.
- Coffee
With a splash of heavy cream and a pinch of Baja Gold mineral salt.
- Sunrise
I take my coffee outside for about 10 minutes. I stand barefoot on the wet grass and watch the sun come up.
- Mid-morning
I take my first dose of magnesium glycinate, away from any dairy.
Tip: wait at least 2 hours after dairy before taking magnesium. Magnesium and calcium compete for absorption.
Protein, a treat, and more sun
- 11 AM–noon, lunch
Full-fat Greek yogurt with a low-carb granola (NuTrail Blueberry Cinnamon Nut Granola) and fruit mix from Costco, plus a can of low-mercury tuna, sardines (King Oscar is my favorite), or wild-caught salmon. Sometimes I add fermented pickles. I always finish with two SkinnyDipped low-sugar dark chocolate peanut butter cups from Costco.
- Supplements
After lunch, I take vitamin K2, vitamin B1 (thiamine), and zinc carnosine.
- After lunch
I try to fit in a walk and some sunshine when I can.
- 2:30 PM
When I get home from work, I always spend at least an hour outdoors to get more sunlight and steps.
- Steps
I average at least 7,000 a day.
Tip: take thiamine at least 90 minutes after your coffee for better absorption.
Simple, outdoors, and consistent
- Strength
I aim for two strength workouts a week, outdoors when the weather allows, using dumbbells and resistance bands.
- Cardio
Besides walking, I use a rebounder (a mini trampoline) for cardio and to keep my lymph moving.
- Next goal
I haven't started sprint intervals yet, but I plan to add them at least once a week.
Early dinner, dim lights, dark room
- 5:30–6:30 PM, dinner
My last meal of the day. Usually some type of red meat (hamburger, steak, roast beef, or beef stew) with a vegetable. A baked potato once or twice a month.
- Sunset
I try to watch the sunset most days. Once the sun goes down, we use only incandescent or red light bulbs. I wear blue-light-blocking glasses if I'm watching TV, and my iPhone screen automatically tints red at night. ▶ How to set up the red screen
- 9:30–10 PM, bedtime supplements
Melatonin (100 mg, my personal dose; I recommend starting at 50 mg), L-theanine (400 mg), glycine (3 g), magnesium glycinate (100 mg), and a teaspoon of inositol powder.
- Bedroom
I use mouth tape to breathe through my nose while I sleep, and a sleep mask to block out any light. We keep the room at 65–67°F. In the fall and spring, we crack the windows open at night for fresh air and to let the cooler temperatures cool the house.
- Unplugging
I unplug the WiFi router and put my phone on airplane mode. This makes for a better sleep environment and reduces nnEMF (non-native electromagnetic fields, the artificial fields from WiFi, phones, and other electronics). Proponents, including neurosurgeon Dr. Jack Kruse, argue that chronic exposure to these artificial fields can disrupt cellular processes, mitochondrial function, calcium signaling, circadian rhythms, sleep, and overall health.
My numbers
I wear an insulin pump connected to my CGM (continuous glucose monitor). As long as I eat low carb and exercise consistently, it keeps my blood sugar in range.
Two beef enchiladas
Once a week I eat two beef enchiladas from one of my favorite local Mexican restaurants. I compromise by skipping the rice, beans, and chips, and I take a small dose of insulin to cover it.
This is what works for me, not a prescription. Talk with your doctor before starting supplements, especially if you take medication or have a health condition.
Do the best you can until you know better. Then when you know better, do better.MAYA ANGELOU
Questions? Email me.
I'd love to hear how the app is working for you, what you'd like to see added, or your own story.
dlacy88@gmail.com Email ↗About the links in this app
I don't currently earn anything from the product links in this app. I recommend them because I use them or trust them. If that changes, I'll clearly mark any affiliate links and update this note.
Everything you enter in this app (your checklist, mood check-ins, grocery list, and numbers) stays on your own device. Nothing is sent to me or anyone else.
FAQ
Is this medical advice?
No. I'm a Certified Functional Nutritional Therapy Practitioner, not a doctor. This app shares general education about nutrition, light, movement, and sleep. Please talk with your doctor before making major changes, especially if you take medication or have a health condition.
Where do the numbers and claims come from?
Each tab has a "Sources for this page" list at the bottom. Tap any small orange number in the app to jump straight to the study or official source behind it.
Do I have to do everything perfectly?
No. It's about progress, not perfection. Start with one or two habits, like morning sunlight and an earlier last meal, and add more as they stick. Eating healthy whole foods 90% of the time will move the needle in a very positive direction.
Do I have to give up bread and carbs?
Not necessarily. Choose better versions, like 3-ingredient sourdough, sprouted grains, white basmati rice, and seasonal fruit. If you're diabetic or eating low carb, keep these limited.
Where is my information stored?
Only on your own phone or computer. Nothing you enter is sent anywhere. If you clear your browser data or switch devices, your checklist history starts fresh.
Do you earn money from the product links?
Not currently. If that changes, affiliate links will be clearly marked.
Last updated November 2026.
Bright days, dark nights
Your circadian rhythm is the foundation of health. A master clock in your brain keeps time for nearly every cell in your body. It runs a little longer than 24 hours, so it needs to be reset every day. The strongest signal that resets it is light hitting your eyes.
How your clock keeps time
- Circadian rhythms are roughly 24-hour biological cycles that regulate your physiology.
- They're controlled by the suprachiasmatic nucleus (SCN) in the hypothalamus.
- Core clock genes (CLOCK, BMAL1, PER, CRY) run feedback loops that regulate sleep, metabolism, and hormone release.
- External cues called zeitgebers, mainly light, dark, and meal timing, keep the clock in sync.
Common circadian disruptors
- Artificial light from screens and LEDs, which suppresses melatonin
- Irregular schedules: shift work, late-night eating, inconsistent sleep
- Social jet lag from sleeping in on weekends
- Staying indoors all day with zero sun exposure
Sunlight = TINA. There is no alternative.DR. JACK KRUSE
Every color of light sends your body a different signal
Sunlight is a full spectrum, from invisible ultraviolet through the colors you see to invisible infrared. Each part does a different job in your biology, and the sun delivers them in a different mix as the day goes on. This section draws on the teachings of circadian educators Dr. Jack Kruse and Sarah Kleiner. Some of these effects are well established, and others are newer ideas still being researched. Tap a band to read about it.
UVB
280–315 nmWhen: midday, when the UV index is 3 or higher
- Makes vitamin D in your skin. Window glass blocks it, so you have to be outside.22
- Switches on POMC in the skin, which makes melanin (your natural sunscreen) and feel-good beta-endorphin.
- Dr. Kruse calls POMC the master gene that links sunlight to your hormones, appetite, and energy.
UVA
315–400 nmWhen: arrives in the morning soon after sunrise and lasts until late afternoon
- Releases nitric oxide from your skin into your blood, which relaxes blood vessels and lowers blood pressure.23
- Sarah Kleiner teaches catching the morning "UVA rise" for about 20 minutes to support appetite regulation and fat burning.
- Morning UVA builds your "solar callus," gradually preparing your skin for the stronger midday sun.
- Dr. Kruse teaches that this frequency turns on your "internal pharmacy," making serotonin and dopamine from aromatic amino acids like tryptophan and tyrosine.
Violet
400–450 nmWhen: all day outdoors, but missing from most LEDs and indoor light
- Detected by neuropsin (OPN5), a light sensor in your eyes and skin.
- Outdoor violet light is being studied for protecting children's eyes from nearsightedness.24
- Dr. Kruse counts it among the frequencies indoor living starves you of.
Blue
450–495 nmWhen: strongest from morning to midday. Should be absent at night.
- The strongest signal to your master clock, through melanopsin cells in your eyes.25
- In the morning it raises healthy cortisol, alertness, and mood, and times tonight's melatonin.
- Dr. Kruse teaches that blue is healthy only when balanced by red and infrared, as it is in sunlight. LEDs and screens give blue without that balance, and at night it suppresses melatonin.
Green & yellow
495–620 nmWhen: all day
- The colors your eyes see best. Most of what makes daylight feel bright.
- Soft green light is being studied for easing migraines and pain.
- Time among green plants and trees is part of why nature calms the nervous system.
Red
620–700 nmWhen: dominant at sunrise and sunset, present all day
- Powers your mitochondria. It activates cytochrome c oxidase, the enzyme that helps make ATP, your cells' energy.26
- The basis of red light therapy, used for skin, recovery, and repair.
- Red doesn't suppress melatonin the way blue does, which is why red night lights are the safe choice after dark.
Near-infrared
700–1400 nmWhen: sunrise to sunset. Roughly half of the sun's energy.
- Penetrates deep into muscle, bone, and brain.
- Dr. Kruse teaches that it makes melatonin inside your mitochondria during the day, protecting cells from damage, and that sunrise infrared prepares your skin for the UV that follows.
- Incandescent bulbs give off near-infrared. LEDs give off almost none.
Far-infrared
1400 nm and upWhen: all day. You feel it as warmth.
- The gentle heat of sunshine, fire, and infrared saunas.
- Warms tissue, improves circulation, and helps your body relax.
- Infrared saunas use it for sweating and recovery.
How the mix of light changes through the day
- Sunrise
Red, near-infrared, and soft blue, with no UV yet. This light sets your clock for the day. Get your eyes on it.
- UVA rise
Shortly after sunrise, once the sun is a little above the horizon, UVA arrives. Morning skin exposure now builds your solar callus.
- Midday
The full spectrum, including UVB, once the UV index reaches 3. This is your vitamin D window, shown on the Today tab.
- Sunset
UV fades, and red and infrared dominate again. Watching the sunset tells your body night is coming.
- Night
Darkness. Only fire, candles, or red light, so melatonin can rise and your body can repair.
Artificial light is a different recipe. LEDs and screens emit a spike of blue with little red and almost no violet, UV, or infrared. Incandescent bulbs and firelight are closer to sunrise and sunset.
Morning light starts the clock
- Triggers a healthy cortisol rise that wakes you up and sets a timer for melatonin about 14–16 hours later.
- Improves mood, alertness, and focus during the day.
- Makes you sleepier at night and helps you fall asleep faster.
- UVB on skin makes vitamin D. Midday sun works best for this, in short doses without burning.
- Being outside is the trick. Even a cloudy sky is many times brighter than indoor lighting.9
Darkness lets the body repair
- Melatonin rises in the dark. Bright light at night suppresses it, even through closed eyelids.
- Deep sleep is when growth hormone peaks and the brain clears waste.27
- Light at night is linked to poorer blood-sugar control, weight gain, and worse mood.28
- Blue and bright overhead light are the strongest signals. Dim, warm, low light is much gentler.
- A room dark enough that you can't see your hand is the goal when sleeping.
Light levels, in lux
Lux measures how much light reaches your eyes. Your clock responds to thousands of lux. Most indoor spaces never come close.
| Setting | Approx. lux | Scale |
|---|
Bar lengths use a log scale, since each step up is roughly ten times brighter.
Daytime habits
- Go outside within 30 minutes of waking. Stay out for 10 min on sunny days, 20–30 min on cloudy ones.
- See the sunrise with your naked eyes: no sunglasses or contacts. Wear your prescription glasses if you need them to see where you are going as you head outside. Once you are seated or stationary, take your glasses off to allow the sunrise light signal to reach your naked eyes.
- Take calls, walks, and coffee outdoors.
- Work near a window. Open the window when possible to let natural light in.
- Crack your windows or open your sunroof when you drive to let natural light in.
- Catch the sunset when you can.
Nighttime & sleep habits
- After sunset, switch off overhead lights. Use lamps, candles, or incandescent bulbs below eye level (strainlesslighting.com).
- No LEDs, screens, or tech for 2 hours before bed.
- Wear blue-light-blocking glasses (orange lenses) if you watch TV at night or are anywhere LED lights are on (midwestredlighttherapy.com).
- Keep a consistent sleep schedule, even on weekends.
- Blackout curtains or a sleep mask.
- Keep the bedroom cool, around 18 °C / 65 °F.
- Mouth tape (Hostage brand) for nasal breathing.
- Unplug the WiFi router before bedtime. Phone on airplane mode, and don't charge it near your bed.
- If you get up at night, use a dim red light.
This app shares general education, not medical advice. Check with your doctor before major changes to diet or exercise, especially if you have a health condition.
Sources for this page (9)
- Gooley JJ, Chamberlain K, Smith KA, et al. Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. Journal of Clinical Endocrinology & Metabolism. 2011;96(3):E463–E472. View source ↗
- Klepeis NE, Nelson WC, Ott WR, et al. The National Human Activity Pattern Survey (NHAPS): a resource for assessing exposure to environmental pollutants. Journal of Exposure Analysis and Environmental Epidemiology. 2001;11(3):231–252. View source ↗
- Holick MF. Vitamin D deficiency. New England Journal of Medicine. 2007;357(3):266–281. View source ↗
- Liu D, Fernandez BO, Hamilton A, et al. UVA irradiation of human skin vasodilates arterial vasculature and lowers blood pressure independently of nitric oxide synthase. Journal of Investigative Dermatology. 2014;134(7):1839–1846. View source ↗
- Torii H, Kurihara T, Seko Y, et al. Violet light exposure can be a preventive strategy against myopia progression. EBioMedicine. 2017;15:210–219. View source ↗
- Berson DM, Dunn FA, Takao M. Phototransduction by retinal ganglion cells that set the circadian clock. Science. 2002;295(5557):1070–1073. View source ↗
- Hamblin MR. Mechanisms and mitochondrial redox signaling in photobiomodulation. Photochemistry and Photobiology. 2018;94(2):199–212. View source ↗
- Xie L, Kang H, Xu Q, et al. Sleep drives metabolite clearance from the adult brain. Science. 2013;342(6156):373–377. View source ↗
- Mason IC, Grimaldi D, Reid KJ, et al. Light exposure during sleep impairs cardiometabolic function. Proceedings of the National Academy of Sciences. 2022;119(12):e2113290119. View source ↗