# 🌿 Cheatsheet: Sleep, Fitness and Energy: Your Physical Foundation

By Better Wise

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One-page lookup card for the whole course. Every entry maps to a lesson. Use the tables to decide, the bullets to act.

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## Module 1: Sleep and Energy Foundations

### 1.1 Sleep Pressure and Your Circadian Clock

Two systems decide how sleepy you feel. They work together but are separate.

| System | What it is | What drives it | Practical lever |
| --- | --- | --- | --- |
| Sleep pressure (Process S) | The "sleep debt" that builds while you are awake | Time awake + how hard you worked your brain and body | Stay awake long enough; take short naps instead of long ones |
| Circadian clock (Process C) | A roughly 24-hour internal rhythm | Light, mainly morning light, plus meal and activity timing | Anchor it with light, meals, and wake time |

```mermaid
flowchart LR
    Wake["🌅<br/>Morning light"] --> Clock["🕒<br/>Circadian clock"]
    Clock --> Alert["⚡<br/>Alertness peak"]
    Awake["⏱️<br/>Hours awake"] --> Pressure["📈<br/>Sleep pressure"]
    Pressure --> Sleepy["😴<br/>Sleep drive"]
    Alert --> Bed["🛏️<br/>Bedtime window"]
    Sleepy --> Bed
```

Key facts:
- Sleep pressure rises the longer you stay awake and drops during sleep.
- The circadian clock sets a daily window of alertness and a window of sleepiness.
- Morning bright light is the strongest anchor for the clock. Late bright light pushes the clock later.
- A short nap (about 20 minutes) lowers sleep pressure without wrecking night sleep. Long late naps can.
- Keeping a consistent wake time is the single easiest way to steady the clock.

### 1.2 Sleep Hygiene That Actually Moves the Needle

Ranked by impact, high to low. Start at the top.