diff --git a/src/app/api/export/measurements/route.ts b/src/app/api/export/measurements/route.ts
index cd3fa45c9..acf4e1dc2 100644
--- a/src/app/api/export/measurements/route.ts
+++ b/src/app/api/export/measurements/route.ts
@@ -37,6 +37,12 @@ export const GET = apiHandler(async (request: NextRequest) => {
 
   const { since, until } = parseRange(request.url);
   const where = buildWhere(user.id, { since, until });
+  // v1.11.5 — sleep export defaults to one row per night; `granularity=raw`
+  // keeps the per-stage rows for power users.
+  const granularity =
+    new URL(request.url).searchParams.get("granularity") === "raw"
+      ? "raw"
+      : "night";
 
   const [measurements, userTz] = await Promise.all([
     prisma.measurement.findMany({
@@ -46,7 +52,12 @@ export const GET = apiHandler(async (request: NextRequest) => {
     resolveUserTimezone(user.id),
   ]);
 
-  const csv = toCSV(formatMeasurementsForExport(measurements, userTz));
+  const csv = toCSV(
+    formatMeasurementsForExport(measurements, userTz, {
+      granularity,
+      sleepTz: userTz,
+    }),
+  );
 
   await auditLog("user.export.measurements", {
     userId: user.id,
diff --git a/src/app/api/export/route.ts b/src/app/api/export/route.ts
index 6b9fc30fe..87b46ca82 100644
--- a/src/app/api/export/route.ts
+++ b/src/app/api/export/route.ts
@@ -61,10 +61,15 @@ export const GET = apiHandler(async (request: NextRequest) => {
       where: { userId, deletedAt: null },
       orderBy: { measuredAt: "desc" },
     });
+    // v1.11.5 — sleep collapses to one row per night by default (the
+    // formatter's `night` granularity), matching the per-type CSV route.
+    const measurementRecords = formatMeasurementsForExport(
+      measurements,
+      userTz,
+      { sleepTz: userTz },
+    );
     data.measurements =
-      format === "csv"
-        ? toCSV(formatMeasurementsForExport(measurements, userTz))
-        : formatMeasurementsForExport(measurements, userTz);
+      format === "csv" ? toCSV(measurementRecords) : measurementRecords;
   }
 
   if (type === "medications" || type === "all") {
diff --git a/src/lib/__tests__/export.test.ts b/src/lib/__tests__/export.test.ts
index cc006fcfc..944a38e69 100644
--- a/src/lib/__tests__/export.test.ts
+++ b/src/lib/__tests__/export.test.ts
@@ -143,6 +143,108 @@ describe("formatMeasurementsForExport", () => {
     const result = formatMeasurementsForExport(measurements);
     expect(result[0].measuredAt).toBe("2026-05-15T09:00:00.000Z");
   });
+
+  // v1.11.5 — sleep collapses to one row per night by default.
+  it("collapses SLEEP_DURATION stage rows to one row per night", () => {
+    const measurements = [
+      {
+        type: "SLEEP_DURATION",
+        value: 240,
+        unit: "minutes",
+        measuredAt: new Date("2026-06-04T03:00:00Z"),
+        source: "APPLE_HEALTH",
+        notes: null,
+        sleepStage: "CORE" as const,
+      },
+      {
+        type: "SLEEP_DURATION",
+        value: 120,
+        unit: "minutes",
+        measuredAt: new Date("2026-06-04T05:00:00Z"),
+        source: "APPLE_HEALTH",
+        notes: null,
+        sleepStage: "DEEP" as const,
+      },
+      {
+        type: "SLEEP_DURATION",
+        value: 120,
+        unit: "minutes",
+        measuredAt: new Date("2026-06-04T07:00:00Z"),
+        source: "APPLE_HEALTH",
+        notes: null,
+        sleepStage: "REM" as const,
+      },
+    ];
+    const result = formatMeasurementsForExport(measurements, "UTC", {
+      sleepTz: "UTC",
+    });
+    // One night row, not three stage rows.
+    expect(result).toHaveLength(1);
+    expect(result[0].type).toBe("SLEEP_DURATION");
+    // TIME ASLEEP = 240 + 120 + 120 = 480 min.
+    expect(result[0].value).toBe(480);
+    // Stage breakdown carried in notes.
+    expect(String(result[0].notes)).toContain("CORE=240m");
+    expect(String(result[0].notes)).toContain("DEEP=120m");
+    expect(String(result[0].notes)).toContain("REM=120m");
+  });
+
+  it("keeps per-stage sleep rows when granularity is raw", () => {
+    const measurements = [
+      {
+        type: "SLEEP_DURATION",
+        value: 240,
+        unit: "minutes",
+        measuredAt: new Date("2026-06-04T03:00:00Z"),
+        source: "APPLE_HEALTH",
+        notes: null,
+        sleepStage: "CORE" as const,
+      },
+      {
+        type: "SLEEP_DURATION",
+        value: 120,
+        unit: "minutes",
+        measuredAt: new Date("2026-06-04T05:00:00Z"),
+        source: "APPLE_HEALTH",
+        notes: null,
+        sleepStage: "DEEP" as const,
+      },
+    ];
+    const result = formatMeasurementsForExport(measurements, "UTC", {
+      granularity: "raw",
+    });
+    expect(result).toHaveLength(2);
+  });
+
+  it("does not collapse non-sleep rows alongside a sleep night", () => {
+    const measurements = [
+      {
+        type: "WEIGHT",
+        value: 80,
+        unit: "kg",
+        measuredAt: new Date("2026-06-04T08:00:00Z"),
+        source: "MANUAL",
+        notes: null,
+      },
+      {
+        type: "SLEEP_DURATION",
+        value: 480,
+        unit: "minutes",
+        measuredAt: new Date("2026-06-04T06:00:00Z"),
+        source: "APPLE_HEALTH",
+        notes: null,
+        sleepStage: "ASLEEP" as const,
+      },
+    ];
+    const result = formatMeasurementsForExport(measurements, "UTC", {
+      sleepTz: "UTC",
+    });
+    expect(result).toHaveLength(2);
+    // Sorted descending by time → WEIGHT (08:00) first, then the sleep night.
+    expect(result[0].type).toBe("WEIGHT");
+    expect(result[1].type).toBe("SLEEP_DURATION");
+    expect(result[1].value).toBe(480);
+  });
 });
 
 describe("formatIntakeEventsForExport with userTz", () => {
diff --git a/src/lib/export.ts b/src/lib/export.ts
index 35e8f0aaf..15ab25432 100644
--- a/src/lib/export.ts
+++ b/src/lib/export.ts
@@ -15,6 +15,12 @@
  * the old contract. Production routes always pass `userTz`.
  */
 import { formatInUserTz } from "./tz/format";
+import {
+  reconstructSleepSessions,
+  pickMainNightAndNaps,
+  type SleepStageRow,
+} from "./analytics/sleep-night";
+import type { SleepStage } from "@/generated/prisma/client";
 
 export interface ExportableRecord {
   [key: string]: unknown;
@@ -80,6 +86,17 @@ function formatTimestamp(date: Date, userTz?: string): string {
   return date.toISOString();
 }
 
+interface ExportMeasurement {
+  type: string;
+  value: number;
+  unit: string;
+  measuredAt: Date;
+  source: string;
+  notes: string | null;
+  glucoseContext?: string | null;
+  sleepStage?: SleepStage | null;
+}
+
 /**
  * Format measurements for export.
  *
@@ -87,20 +104,22 @@ function formatTimestamp(date: Date, userTz?: string): string {
  * ISO-8601 with the user's UTC offset (e.g. `+02:00` in Berlin in
  * May) instead of the bare `Z` suffix. See module-level docstring
  * for the rationale (issue #167).
+ *
+ * v1.11.5 — SLEEP_DURATION is stored one row per STAGE per night. A flat
+ * export emitted a wall of per-stage minutes with no night attribution.
+ * By default sleep rows are now COLLAPSED to one record per night (the
+ * main session's TIME ASLEEP per the nap convention) carrying the stage
+ * breakdown in `notes` so the single uniform CSV reads as one night, not
+ * many stages. Pass `granularity: "raw"` to keep the per-stage rows for
+ * power users. Storage is untouched either way.
  */
 export function formatMeasurementsForExport(
-  measurements: Array<{
-    type: string;
-    value: number;
-    unit: string;
-    measuredAt: Date;
-    source: string;
-    notes: string | null;
-    glucoseContext?: string | null;
-  }>,
+  measurements: ExportMeasurement[],
   userTz?: string,
+  opts: { granularity?: "night" | "raw"; sleepTz?: string } = {},
 ): ExportableRecord[] {
-  return measurements.map((m) => ({
+  const granularity = opts.granularity ?? "night";
+  const toRecord = (m: ExportMeasurement): ExportableRecord => ({
     type: m.type,
     value: m.value,
     unit: m.unit,
@@ -108,7 +127,73 @@ export function formatMeasurementsForExport(
     source: m.source,
     notes: m.notes ?? "",
     glucoseContext: m.glucoseContext ?? "",
+  });
+
+  if (granularity === "raw") {
+    return measurements.map(toRecord);
+  }
+
+  // Split sleep stage rows out, collapse them per night, and merge back
+  // in chronological order with the non-sleep rows.
+  const sleepRows = measurements.filter((m) => m.type === "SLEEP_DURATION");
+  if (sleepRows.length === 0) {
+    return measurements.map(toRecord);
+  }
+  const other = measurements.filter((m) => m.type !== "SLEEP_DURATION");
+  // `reconstructSleepSessions` clusters by wake-day using the user's tz;
+  // fall back to UTC when no tz is threaded (admin / on-disk shape).
+  const tz = opts.sleepTz ?? userTz ?? "UTC";
+  const stageRows: SleepStageRow[] = sleepRows.map((m) => ({
+    value: m.value,
+    measuredAt: m.measuredAt,
+    sleepStage: m.sleepStage ?? null,
+    source: m.source as SleepStageRow["source"],
   }));
+  const sessions = reconstructSleepSessions(stageRows, tz);
+  const byDay = new Map<string, typeof sessions>();
+  for (const s of sessions) {
+    const list = byDay.get(s.night) ?? [];
+    list.push(s);
+    byDay.set(s.night, list);
+  }
+  const nightRecords: Array<{ at: Date; rec: ExportableRecord }> = [];
+  for (const daySessions of byDay.values()) {
+    const { main, naps } = pickMainNightAndNaps(daySessions);
+    if (!main) continue;
+    const stageParts = (Object.entries(main.stages) as Array<[string, number]>)
+      .filter(([, mins]) => mins > 0)
+      .map(([stage, mins]) => `${stage}=${Math.round(mins)}m`)
+      .join(" ");
+    const napNote =
+      naps.length > 0
+        ? ` naps=${naps.length}(${Math.round(
+            naps.reduce((sum, n) => sum + n.asleepMinutes, 0),
+          )}m)`
+        : "";
+    const awakeningNote =
+      main.awakenings > 0 ? ` awakenings=${main.awakenings}` : "";
+    nightRecords.push({
+      at: main.end,
+      rec: {
+        type: "SLEEP_DURATION",
+        // Headline value = the main night's TIME ASLEEP in minutes.
+        value: Math.round(main.asleepMinutes),
+        unit: "minutes",
+        measuredAt: formatTimestamp(main.end, userTz),
+        source: main.source ?? "",
+        notes: `${stageParts}${napNote}${awakeningNote}`.trim(),
+        glucoseContext: "",
+      },
+    });
+  }
+
+  // Merge: keep the same descending-by-time order the route reads in.
+  const merged: Array<{ at: Date; rec: ExportableRecord }> = [
+    ...other.map((m) => ({ at: m.measuredAt, rec: toRecord(m) })),
+    ...nightRecords,
+  ];
+  merged.sort((a, b) => b.at.getTime() - a.at.getTime());
+  return merged.map((x) => x.rec);
 }
 
 /**