"dead sleep" meaning in English

{
  "antonyms": [
    {
      "word": "morning sleep"
    }
  ],
  "forms": [
    {
      "form": "dead sleeps",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "-",
        "2": "s"
      },
      "expansion": "dead sleep (usually uncountable, plural dead sleeps)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "glosses": [
        "A particularly sound sleep"
      ],
      "id": "en-dead_sleep-en-noun-HkfeodWn",
      "links": [
        [
          "sound",
          "sound"
        ]
      ],
      "tags": [
        "uncountable",
        "usually"
      ]
    },
    {
      "categories": [
        {
          "_dis": "5 95",
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "12 88",
          "kind": "other",
          "name": "English entries with topic categories using raw markup",
          "parents": [
            "Entries with topic categories using raw markup",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "13 87",
          "kind": "other",
          "name": "English terms with non-redundant non-automated sortkeys",
          "parents": [
            "Terms with non-redundant non-automated sortkeys",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "32 68",
          "kind": "topical",
          "langcode": "en",
          "name": "Sleep",
          "orig": "en:Sleep",
          "parents": [
            "Body",
            "Human",
            "All topics",
            "Fundamental"
          ],
          "source": "w+disamb"
        }
      ],
      "examples": [
        {
          "ref": "2001 April, A. Roger Ekirch, “Sleep We Have Lost: Pre-Industrial Slumber in the British Isles”, in The American Historical Review, volume 106, number 2, American Historical Association, page 364",
          "text": "Until the close of the early modern era, Western Europeans on most evenings experienced two major intervals of sleep bridged by up to an hour or more of quiet wakefulness. […] The initial interval of slumber was usually referred to as “first sleep,” or, less often, “first nap” or “dead sleep.”",
          "type": "quotation"
        }
      ],
      "glosses": [
        "The first sleep of the night in a biphasic sleep pattern, before the watch."
      ],
      "id": "en-dead_sleep-en-noun-tzybMAxZ",
      "links": [
        [
          "sleep",
          "sleep"
        ],
        [
          "biphasic sleep",
          "biphasic sleep"
        ],
        [
          "watch",
          "watch"
        ]
      ],
      "synonyms": [
        {
          "_dis1": "16 84",
          "sense": "first sleep of the night",
          "word": "first sleep"
        }
      ],
      "tags": [
        "uncountable",
        "usually"
      ],
      "translations": [
        {
          "_dis1": "29 71",
          "code": "fr",
          "lang": "French",
          "sense": "first sleep",
          "word": "premier somme"
        },
        {
          "_dis1": "29 71",
          "code": "it",
          "lang": "Italian",
          "sense": "first sleep",
          "word": "primo sonno"
        },
        {
          "_dis1": "29 71",
          "code": "la",
          "lang": "Latin",
          "sense": "first sleep",
          "word": "primus somnus"
        },
        {
          "_dis1": "29 71",
          "code": "la",
          "lang": "Latin",
          "sense": "first sleep",
          "word": "concubia nocte"
        }
      ]
    }
  ],
  "word": "dead sleep"
}

{
  "antonyms": [
    {
      "word": "morning sleep"
    }
  ],
  "categories": [
    "English countable nouns",
    "English entries with incorrect language header",
    "English entries with topic categories using raw markup",
    "English lemmas",
    "English multiword terms",
    "English nouns",
    "English terms with non-redundant non-automated sortkeys",
    "English uncountable nouns",
    "en:Sleep"
  ],
  "forms": [
    {
      "form": "dead sleeps",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "-",
        "2": "s"
      },
      "expansion": "dead sleep (usually uncountable, plural dead sleeps)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "glosses": [
        "A particularly sound sleep"
      ],
      "links": [
        [
          "sound",
          "sound"
        ]
      ],
      "tags": [
        "uncountable",
        "usually"
      ]
    },
    {
      "categories": [
        "English terms with quotations"
      ],
      "examples": [
        {
          "ref": "2001 April, A. Roger Ekirch, “Sleep We Have Lost: Pre-Industrial Slumber in the British Isles”, in The American Historical Review, volume 106, number 2, American Historical Association, page 364",
          "text": "Until the close of the early modern era, Western Europeans on most evenings experienced two major intervals of sleep bridged by up to an hour or more of quiet wakefulness. […] The initial interval of slumber was usually referred to as “first sleep,” or, less often, “first nap” or “dead sleep.”",
          "type": "quotation"
        }
      ],
      "glosses": [
        "The first sleep of the night in a biphasic sleep pattern, before the watch."
      ],
      "links": [
        [
          "sleep",
          "sleep"
        ],
        [
          "biphasic sleep",
          "biphasic sleep"
        ],
        [
          "watch",
          "watch"
        ]
      ],
      "tags": [
        "uncountable",
        "usually"
      ]
    }
  ],
  "synonyms": [
    {
      "sense": "first sleep of the night",
      "word": "first sleep"
    }
  ],
  "translations": [
    {
      "code": "fr",
      "lang": "French",
      "sense": "first sleep",
      "word": "premier somme"
    },
    {
      "code": "it",
      "lang": "Italian",
      "sense": "first sleep",
      "word": "primo sonno"
    },
    {
      "code": "la",
      "lang": "Latin",
      "sense": "first sleep",
      "word": "primus somnus"
    },
    {
      "code": "la",
      "lang": "Latin",
      "sense": "first sleep",
      "word": "concubia nocte"
    }
  ],
  "word": "dead sleep"
}