Sleep Stages and What They Do
A normal night cycles through 4–6 stages every 90 minutes. Each stage serves a distinct function — disrupting any of them produces specific symptoms.
Light sleep (N1, N2)
50–60% of total sleep. Memory consolidation, motor learning. Easily disturbed.
Deep sleep (N3 / slow-wave)
13–23% of total. Physical recovery, growth hormone release, glymphatic clearance. Concentrated in first half of night.
REM sleep
20–25% of total. Emotional processing, creative consolidation, neural pruning. Concentrated in second half.
Wake-after-sleep-onset (WASO)
Should be < 30 minutes total. Frequent wakings fragment architecture.
The Circadian Foundation
Sleep quality is set hours before bed by circadian inputs. The two highest-leverage levers are morning light and evening light avoidance.
- 1Morning light: 10+ minutes of outdoor light within 30 minutes of waking. Anchors the circadian clock.
- 2Bright light avoidance after sunset: Dim ambient light, warm-color bulbs, no overhead fluorescents
- 3Screens: Blue-light filters help; brightness reduction helps more; avoiding screens entirely after 9pm helps most
- 4Consistent timing: Wake at the same time daily, including weekends. Bedtime drift is normal; wake-time drift wrecks the rhythm
If you only do one thing
Get 10 minutes of outdoor light within 30 minutes of waking. This single behavior change improves sleep onset, depth, and morning energy more than any supplement.
Temperature: The Underrated Lever
Core body temperature must drop 2–3°F for sleep onset. The body manages this by routing blood to the extremities. You can accelerate it.
- Bedroom temperature: 65–68°F (18–20°C). Cooler than feels comfortable when awake
- Hot shower 1–2 hours before bed: Counterintuitively cools the core via reactive vasodilation
- Cooling mattress pads: Highest-leverage hardware investment if you run hot or share a bed
- Sock trick: Warm socks dilate foot vasculature, accelerate heat loss, speed sleep onset
Substances: The Big Three
Three commonly-used substances do more to wreck sleep than anything else. Address these before optimizing further.
- 1Caffeine: Half-life 5–6 hours. Cutoff 10 hours before bed. The 'I sleep fine after coffee' people are usually wrong about depth
- 2Alcohol: Suppresses REM in the first half, causes mid-night wakings. The single highest-leverage cut for many people
- 3Cannabis: Suppresses REM in the short term. Tolerance builds; withdrawal causes vivid dreams and insomnia
Supplementation Stack
Supplements are the last 10%. They cannot fix bad behavior. Used correctly, a small stack improves depth and onset.
Magnesium glycinate
200–400mg, 30 minutes before bed. Calms nervous system, improves depth.
Glycine
3g sublingual or in water. Lowers core temperature, improves subjective sleep quality.
Apigenin
50mg from chamomile extract. GABA-ergic, useful for racing thoughts.
L-Theanine
200mg. Reduces sleep latency, especially when combined with magnesium.
Skip melatonin (mostly)
Melatonin is a circadian signal, not a sedative. Useful for jet lag at 0.3–0.5mg; the 5–10mg doses sold in stores are 10–30x physiological levels and produce next-day grogginess.
Fixing Fragmentation
The 3am wake-up is usually one of three causes. Diagnose before treating.
- Blood sugar crash: Common after sugar-heavy dinners or alcohol. A small protein-fat snack can prevent it
- Cortisol spike: Stress-driven. Address the upstream stress; magnesium and glycine help acutely
- Sleep apnea: If you snore, gasp, or wake unrefreshed despite duration — get a sleep study. Untreated apnea wrecks everything else
Implementation Checklist
- 110 minutes of outdoor morning light, daily
- 2Caffeine cutoff at 10 hours before bedtime
- 3Bedroom temperature 65–68°F
- 4Same wake time, 7 days/week (within 30 minutes)
- 5No alcohol within 3 hours of bed (zero is better)
- 6Magnesium glycinate + glycine stack 30 minutes before bed
- 7Track sleep duration and consistency for 4 weeks before assessing changes