{
  "slug": "sleep-time",
  "title": "Sleep Cycle Calculator",
  "heading": "Sleep Cycle Calculator",
  "category": "other",
  "url": "https://www.revenuelab.fyi/toolbox/sleep-time",
  "summary": "Bedtimes that let you wake between sleep cycles.",
  "description": "A full sleep cycle runs about 90 minutes. Waking at the end of a cycle rather than mid-cycle is why six hours can feel better than seven.",
  "formula": "Bedtime = Wake time − (cycles × 90 minutes) − time to fall asleep.",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=sleep-time",
  "inputs": [
    {
      "id": "wakeH",
      "label": "Wake hour (0–23)",
      "kind": "number",
      "hint": null,
      "default": 6,
      "unit": null,
      "min": 0,
      "max": 23
    },
    {
      "id": "wakeM",
      "label": "Wake minute",
      "kind": "number",
      "hint": null,
      "default": 30,
      "unit": null,
      "min": 0,
      "max": 59
    },
    {
      "id": "fallAsleep",
      "label": "Minutes to fall asleep",
      "kind": "number",
      "hint": null,
      "default": 15,
      "unit": null,
      "min": 0,
      "max": 90
    },
    {
      "id": "cycles",
      "label": "Target sleep cycles",
      "kind": "number",
      "hint": null,
      "default": 5,
      "unit": null,
      "min": 3,
      "max": 7
    }
  ],
  "outputs": [
    {
      "id": "best",
      "label": "Ideal bedtime",
      "format": "raw",
      "hint": null,
      "primary": true
    },
    {
      "id": "alt1",
      "label": "One cycle later",
      "format": "raw",
      "hint": null,
      "primary": false
    },
    {
      "id": "alt2",
      "label": "One cycle earlier",
      "format": "raw",
      "hint": null,
      "primary": false
    },
    {
      "id": "hours",
      "label": "Hours asleep",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "totalMinutes",
      "label": "Total time in bed (min)",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "cycles",
      "label": "Sleep cycles",
      "format": "number",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Wake hour (0–23): 6",
      "Wake minute: 30",
      "Minutes to fall asleep: 15",
      "Target sleep cycles: 5"
    ],
    "outputs": [
      "Ideal bedtime: 10:45 PM",
      "One cycle later: 12:15 AM",
      "One cycle earlier: 9:15 PM",
      "Hours asleep: 7.5",
      "Total time in bed (min): 465",
      "Sleep cycles: 5"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter wake hour (0–23).",
      "Enter wake minute.",
      "Enter minutes to fall asleep.",
      "Enter target sleep cycles.",
      "Read your ideal bedtime on the right — it updates as you type.",
      "Hit Share to keep the scenario or send it to someone."
    ]
  },
  "scenarios": [
    {
      "name": "Conservative",
      "description": "Lower-end numbers — what if things land soft?",
      "values": {
        "wakeH": 4,
        "wakeM": 20,
        "fallAsleep": 10,
        "cycles": 3
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "wakeH": 6,
        "wakeM": 30,
        "fallAsleep": 15,
        "cycles": 5
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "wakeH": 10,
        "wakeM": 50,
        "fallAsleep": 25,
        "cycles": 7
      }
    }
  ],
  "limitations": [
    "Estimates assume standard, average conditions — local rules, pricing, and materials vary.",
    "Results are rounded for readability; add a buffer before ordering, booking, or committing.",
    "Double-check anything with a real cost attached against a local quote."
  ],
  "faq": [
    {
      "q": "How does the sleep cycle calculator work?",
      "a": "A full sleep cycle runs about 90 minutes. Waking at the end of a cycle rather than mid-cycle is why six hours can feel better than seven. The underlying maths is: Bedtime = Wake time − (cycles × 90 minutes) − time to fall asleep."
    },
    {
      "q": "What do I need to enter?",
      "a": "4 values: wake hour (0–23), wake minute, minutes to fall asleep, and target sleep cycles. Each field starts with a sensible default, so you can change one number at a time and watch the result move."
    },
    {
      "q": "What does the ideal bedtime result mean?",
      "a": "It is returned as a plain value and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds."
    },
    {
      "q": "Is this calculator free, and do I need an account?",
      "a": "Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser."
    },
    {
      "q": "How accurate is the result?",
      "a": "It applies the standard formula exactly, so the arithmetic is precise. Estimates assume standard, average conditions — local rules, pricing, and materials vary."
    },
    {
      "q": "Who is this tool for?",
      "a": "It's built for anyone doing everyday planning maths — a quick estimate that would otherwise need four browser tabs and a calculator app."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/time-duration",
    "https://www.revenuelab.fyi/toolbox/countdown-days"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Sleep Cycle Calculator (https://www.revenuelab.fyi/toolbox/sleep-time)"
}