{
    "name": "Sleep Calculator",
    "url": "https://calculators.geekmidst.com/calculators/sleep-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/sleep-calculator.md",
    "category": "Everyday tools",
    "description": "Find bedtimes that fit a set wake-up time, or wake-up times for a given bedtime, by counting roughly 90-minute sleep cycles plus time to fall asleep.",
    "summary": "Sleep runs in cycles that average about 90 minutes. Planning to wake at the end of a cycle rather than in the middle of one may help you feel less groggy.",
    "also_called": [
        "Bedtime calculator",
        "Sleep cycle calculator",
        "Wake-up time calculator"
    ],
    "applies_to": "Worldwide",
    "last_updated": "2026-10-29",
    "computation": "Results are computed in the visitor’s browser on the HTML page. This API describes the calculator; it does not compute results.",
    "inputs": [
        {
            "name": "mode",
            "label": "I know",
            "type": "segmented",
            "default": "wake",
            "options": {
                "wake": "When I must wake up",
                "bed": "When I go to bed"
            }
        },
        {
            "name": "time",
            "label": "Time",
            "type": "time",
            "default": "07:00"
        },
        {
            "name": "latency",
            "label": "Time to fall asleep",
            "type": "number",
            "default": "15",
            "unit": "min"
        },
        {
            "name": "cycle",
            "label": "Cycle length",
            "type": "number",
            "default": "90",
            "unit": "min"
        }
    ],
    "outputs": [
        {
            "key": "five_cycles",
            "label": "5 cycles (7.5 h asleep)",
            "format": "text"
        },
        {
            "key": "six_cycles",
            "label": "6 cycles (9 h asleep)",
            "format": "text"
        },
        {
            "key": "four_cycles",
            "label": "4 cycles (6 h asleep)",
            "format": "text"
        },
        {
            "key": "sleep_hours_five",
            "label": "Sleep in 5 cycles",
            "format": "number"
        }
    ],
    "formula": {
        "text": "Bedtime = Wake-up time − Time to fall asleep − Cycles × Cycle length;  Wake-up time = Bedtime + Time to fall asleep + Cycles × Cycle length",
        "variables": {
            "Cycle length": "about 90 minutes on average",
            "Time to fall asleep": "typically 10–20 minutes"
        }
    },
    "worked_example": {
        "inputs": {
            "mode": "wake",
            "time": "07:00",
            "latency": "15",
            "cycle": "90"
        },
        "steps": [
            "Five cycles = 5 × 90 = 450 minutes = 7 h 30 min of sleep.",
            "07:00 − 7 h 30 min − 15 min to fall asleep = 23:15.",
            "Six cycles (9 h) moves bedtime 90 minutes earlier, to 21:45."
        ],
        "result": "To wake at 7:00 am after five full cycles, be in bed by about 11:15 pm."
    },
    "interpretation": "The American Academy of Sleep Medicine recommends that adults get 7 or more hours a night, so five or six cycles is the usual target. Four cycles (6 hours) is short for most adults.",
    "assumptions": [
        "Every cycle is the same length. Real cycles vary from about 70 to 120 minutes and change through the night.",
        "You fall asleep in the time entered."
    ],
    "limitations": [
        "A cycle-based time is a rough guide, not a guarantee of waking at the end of a cycle.",
        "This tool does not assess sleep disorders. Persistent tiredness despite enough sleep is worth discussing with a doctor."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "How long is a sleep cycle?",
            "answer": "About 90 minutes on average. Early cycles are often shorter and later ones longer, and a typical night has four to six."
        },
        {
            "question": "How much sleep do adults need?",
            "answer": "The American Academy of Sleep Medicine recommends 7 or more hours per night for adults."
        }
    ],
    "sources": [
        {
            "title": "Sleep Foundation — Stages of Sleep",
            "url": "https://www.sleepfoundation.org/how-sleep-works/stages-of-sleep"
        },
        {
            "title": "AASM Sleep Education — How much sleep do I really need?",
            "url": "https://sleepeducation.org/how-much-sleep-do-i-really-need/"
        }
    ],
    "related": [
        {
            "name": "Time Duration Calculator",
            "url": "https://calculators.geekmidst.com/calculators/time-duration-calculator"
        },
        {
            "name": "Age Calculator",
            "url": "https://calculators.geekmidst.com/calculators/age-calculator"
        },
        {
            "name": "BMR Calculator",
            "url": "https://calculators.geekmidst.com/calculators/bmr-calculator"
        }
    ],
    "disclaimer": "This is a general screening estimate for adults, not medical advice or a diagnosis. Talk to a qualified health professional about your health.",
    "publisher": "GM¹X CalcVerse"
}