← LCCSLEEP
Sleep Cheat Sheet
  • Fixed wake time: Wake at the same time every day (including weekends). This anchors your circadian rhythm
  • Dark room: Use blackout curtains or sleep mask. Even a small light source suppresses melatonin
  • Cool temperature: 18–21°C is the optimal sleep temperature. A slight drop in body temp triggers sleep onset
  • No screens 45–60 min before bed: Blue light suppresses melatonin and delays sleep onset by 1–3 hours
  • No alcohol: Alcohol disrupts REM sleep — you may fall asleep faster but sleep quality is significantly worse
  • No large meals 2–3h before bed: Digestion raises core temperature and interrupts sleep cycles
  • Bed = sleep only: Avoid working, eating, or scrolling in bed — brain stops associating bed with sleep
  • Consistent sleep window: 7–9 hours. Quality > quantity, but both matter
★The single highest-ROI sleep habit: FIXED WAKE TIME. Even after a bad night, wake at the same time — sleep drive builds and the next night recovers naturally.
  1. T-60 min: Dim lights — Switch to warm/dim lighting in the room. Signal brain that evening has arrived
  2. T-45 min: Screens off — Phone face-down or in another room (social media at night = mental activation + anxiety)
  3. T-40 min: Light activity — Reading physical book, gentle stretching, journaling, light conversation. Nothing stimulating
  4. T-20 min: Shower or warm bath — Warm shower 1–2h before bed drops core body temperature post-shower = faster sleep onset
  5. T-10 min: Brain dump (optional) — Write tomorrow's to-do list on paper. Offloads working memory, reduces pre-sleep rumination
  6. T-0: Lie down, same time — Breathe slowly. If not asleep in 20 min, leave bed, do something calm, return when sleepy
DrinkCaffeine (mg)Half-lifeLatest Safe Consumption
Espresso (single shot)635–6 hours2:00 PM (for 10 PM bedtime)
Filter coffee (250ml)95–1205–6 hours12:30 PM (for 10 PM bedtime)
Instant coffee (250ml)60–805–6 hours1:00 PM
Black tea (250ml)40–705–6 hours2:00 PM
Green tea (250ml)25–355–6 hours3:00 PM
Cola drink (500ml)35–505–6 hours3:00 PM
Dark chocolate (50g)20–305–6 hours4:00 PM
★Caffeine half-life is 5–6 hours. If you have a coffee at 3PM, 50% is still in your system at 9PM, disrupting sleep depth even if you fall asleep normally.
Can you catch up on weekends?
Partially. Short-term sleep debt can be partially recovered. Chronic sleep debt (weeks) is not fully reversible by weekend sleep
Naps
20–25 min max (before 3 PM). Longer = sleep inertia + disrupts night sleep. "Coffee nap" = coffee immediately before nap, wake when caffeine kicks in
Signs of chronic sleep deprivation
Constant drowsiness, needing alarm to wake, mood swings, poor concentration, cravings for sugar/fat
Sleep trackers
Useful for trends but not clinically accurate for sleep stages. Use as motivational tool, not medical measurement