diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/ComputedHrvSummarySampleProvider.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/ComputedHrvSummarySampleProvider.java
index 7f9043755b..01beb69811 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/ComputedHrvSummarySampleProvider.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/ComputedHrvSummarySampleProvider.java
@@ -26,6 +26,10 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
+import nodomain.freeyourgadget.gadgetbridge.activities.charts.SleepAnalysis;
+import nodomain.freeyourgadget.gadgetbridge.entities.AbstractActivitySample;
+import nodomain.freeyourgadget.gadgetbridge.entities.DaoSession;
+import nodomain.freeyourgadget.gadgetbridge.impl.GBDevice;
 import nodomain.freeyourgadget.gadgetbridge.model.HrvSummarySample;
 import nodomain.freeyourgadget.gadgetbridge.model.HrvValueSample;
 
@@ -36,7 +40,7 @@ import nodomain.freeyourgadget.gadgetbridge.model.HrvValueSample;
  * <p>
  * The provider calculates:
  * - Weekly average (7-day rolling average of all HRV values)
- * - Last night average and 5-min high (8 hours before midnight to midnight)
+ * - Last night average and 5-min high (based on actual sleep sessions detected from activity data)
  * - Baseline values using Garmin's method: mean ± standard deviation of 28 overnight averages
  * <p>
  * Summaries are computed on-demand and cached for performance.
@@ -47,6 +51,8 @@ public class ComputedHrvSummarySampleProvider implements TimeSampleProvider<HrvS
     private static final int CACHE_SIZE = 100; // Cache up to 100 computed summaries
 
     private final TimeSampleProvider<? extends HrvValueSample> valueProvider;
+    private final GBDevice device;
+    private final DaoSession session;
 
     // LRU cache for computed summaries
     private final Map<Long, HrvSummarySample> summaryCache = new LinkedHashMap<>(CACHE_SIZE, 0.75f, true) {
@@ -56,8 +62,12 @@ public class ComputedHrvSummarySampleProvider implements TimeSampleProvider<HrvS
         }
     };
 
-    public ComputedHrvSummarySampleProvider(final TimeSampleProvider<? extends HrvValueSample> valueProvider) {
+    public ComputedHrvSummarySampleProvider(final TimeSampleProvider<? extends HrvValueSample> valueProvider,
+                                           final GBDevice device,
+                                           final DaoSession session) {
         this.valueProvider = valueProvider;
+        this.device = device;
+        this.session = session;
     }
 
     @NonNull
@@ -133,12 +143,50 @@ public class ComputedHrvSummarySampleProvider implements TimeSampleProvider<HrvS
         weekStart.add(Calendar.DATE, -DAYS_FOR_WEEKLY_AVG + 1);
         final int weeklyAvg = calculateAverageHrv(weekStart.getTimeInMillis(), dayEndTimestamp);
 
-        // Calculate last night average (previous night, 8 hours before midnight to midnight)
-        final Calendar lastNightEnd = (Calendar) dayStart.clone();
-        final Calendar lastNightStart = (Calendar) lastNightEnd.clone();
-        lastNightStart.add(Calendar.HOUR_OF_DAY, -8); // 8 hours back from midnight
-        final int lastNightAvg = calculateAverageHrv(lastNightStart.getTimeInMillis(), lastNightEnd.getTimeInMillis());
-        final int lastNight5MinHigh = calculate5MinHighHrv(lastNightStart.getTimeInMillis(), lastNightEnd.getTimeInMillis());
+        // Calculate last night average using actual sleep sessions
+        // Get activity samples for a 24-hour window that should contain the previous night's sleep
+        // (from noon of previous day to noon of current day)
+        final Calendar searchStart = (Calendar) dayStart.clone();
+        searchStart.add(Calendar.DATE, -1);
+        searchStart.set(Calendar.HOUR_OF_DAY, 12);
+        searchStart.set(Calendar.MINUTE, 0);
+        searchStart.set(Calendar.SECOND, 0);
+        searchStart.set(Calendar.MILLISECOND, 0);
+
+        final Calendar searchEnd = (Calendar) dayStart.clone();
+        searchEnd.set(Calendar.HOUR_OF_DAY, 12);
+        searchEnd.set(Calendar.MINUTE, 0);
+        searchEnd.set(Calendar.SECOND, 0);
+        searchEnd.set(Calendar.MILLISECOND, 0);
+
+        final int startTs = (int) (searchStart.getTimeInMillis() / 1000);
+        final int endTs = (int) (searchEnd.getTimeInMillis() / 1000);
+
+        int lastNightAvg = 0;
+        int lastNight5MinHigh = 0;
+
+        // Get activity samples and calculate sleep sessions
+        final SampleProvider<? extends AbstractActivitySample> sampleProvider =
+            device.getDeviceCoordinator().getSampleProvider(device, session);
+        final List<? extends AbstractActivitySample> activitySamples =
+            sampleProvider.getAllActivitySamples(startTs, endTs);
+
+        if (!activitySamples.isEmpty()) {
+            final SleepAnalysis sleepAnalysis = new SleepAnalysis();
+            final List<SleepAnalysis.SleepSession> sleepSessions =
+                sleepAnalysis.calculateSleepSessions(activitySamples);
+
+            // Use the last (most recent) sleep session - this should be the previous night
+            // SleepAnalysis returns sessions with their actual start/end times
+            if (!sleepSessions.isEmpty()) {
+                final SleepAnalysis.SleepSession lastSession = sleepSessions.get(sleepSessions.size() - 1);
+                final long sessionStart = lastSession.getSleepStart().getTime();
+                final long sessionEnd = lastSession.getSleepEnd().getTime();
+
+                lastNightAvg = calculateAverageHrv(sessionStart, sessionEnd);
+                lastNight5MinHigh = calculate5MinHighHrv(sessionStart, sessionEnd);
+            }
+        }
 
         // Calculate baseline values (using past 28 overnight averages)
         final BaselineValues baseline = calculateBaseline(dayEndTimestamp);
@@ -206,30 +254,52 @@ public class ComputedHrvSummarySampleProvider implements TimeSampleProvider<HrvS
         final Calendar cal = Calendar.getInstance();
         cal.setTimeInMillis(timestampTo);
 
+        final SampleProvider<? extends AbstractActivitySample> sampleProvider =
+            device.getDeviceCoordinator().getSampleProvider(device, session);
+        final SleepAnalysis sleepAnalysis = new SleepAnalysis();
+
         // Collect overnight averages for the past 28 days
         for (int i = 0; i < DAYS_FOR_BASELINE; i++) {
-            // Define "overnight" as 8 hours before midnight to midnight
-            final Calendar dayStart = (Calendar) cal.clone();
-            dayStart.set(Calendar.HOUR_OF_DAY, 0);
-            dayStart.set(Calendar.MINUTE, 0);
-            dayStart.set(Calendar.SECOND, 0);
-            dayStart.set(Calendar.MILLISECOND, 0);
+            // Get activity samples for a 24-hour window (noon to noon) to find sleep sessions
+            final Calendar searchEnd = (Calendar) cal.clone();
+            searchEnd.set(Calendar.HOUR_OF_DAY, 12);
+            searchEnd.set(Calendar.MINUTE, 0);
+            searchEnd.set(Calendar.SECOND, 0);
+            searchEnd.set(Calendar.MILLISECOND, 0);
 
-            final Calendar nightStart = (Calendar) dayStart.clone();
-            nightStart.add(Calendar.HOUR_OF_DAY, -8);
+            final Calendar searchStart = (Calendar) searchEnd.clone();
+            searchStart.add(Calendar.DATE, -1);
 
-            final int nightAvg = calculateAverageHrv(nightStart.getTimeInMillis(), dayStart.getTimeInMillis());
-            if (nightAvg > 0) {
-                overnightAverages.add(nightAvg);
+            final int startTs = (int) (searchStart.getTimeInMillis() / 1000);
+            final int endTs = (int) (searchEnd.getTimeInMillis() / 1000);
+
+            final List<? extends AbstractActivitySample> activitySamples =
+                sampleProvider.getAllActivitySamples(startTs, endTs);
+
+            if (!activitySamples.isEmpty()) {
+                final List<SleepAnalysis.SleepSession> sleepSessions =
+                    sleepAnalysis.calculateSleepSessions(activitySamples);
+
+                // Use the last sleep session in the window (should be the previous night)
+                if (!sleepSessions.isEmpty()) {
+                    final SleepAnalysis.SleepSession lastSession = sleepSessions.get(sleepSessions.size() - 1);
+                    final long sessionStart = lastSession.getSleepStart().getTime();
+                    final long sessionEnd = lastSession.getSleepEnd().getTime();
+
+                    final int nightAvg = calculateAverageHrv(sessionStart, sessionEnd);
+                    if (nightAvg > 0) {
+                        overnightAverages.add(nightAvg);
+                    }
+                }
             }
 
             // Move to previous day
             cal.add(Calendar.DATE, -1);
         }
 
-        // Require at least 7 days of overnight data before calculating a baseline
+        // Require at least DAYS_FOR_WEEKLY_AVG of overnight data before calculating a baseline
         // This prevents unreliable status calculations in the first few days
-        if (overnightAverages.size() < 7) {
+        if (overnightAverages.size() < DAYS_FOR_WEEKLY_AVG) {
             return new BaselineValues(0, 0, 0);
         }
 
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/huami/HuamiCoordinator.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/huami/HuamiCoordinator.java
index d65cd01c4f..ab15ce8f98 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/huami/HuamiCoordinator.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/huami/HuamiCoordinator.java
@@ -212,7 +212,7 @@ public abstract class HuamiCoordinator extends AbstractBLEDeviceCoordinator {
 
     @Override
     public TimeSampleProvider<? extends HrvSummarySample> getHrvSummarySampleProvider(GBDevice device, DaoSession session) {
-        return new ComputedHrvSummarySampleProvider(getHrvValueSampleProvider(device, session));
+        return new ComputedHrvSummarySampleProvider(getHrvValueSampleProvider(device, session), device, session);
     }
 
     @Override
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/ultrahuman/UltrahumanDeviceCoordinator.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/ultrahuman/UltrahumanDeviceCoordinator.java
index 29d46c4872..45278797b4 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/ultrahuman/UltrahumanDeviceCoordinator.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/ultrahuman/UltrahumanDeviceCoordinator.java
@@ -154,7 +154,7 @@ public class UltrahumanDeviceCoordinator extends AbstractBLEDeviceCoordinator {
 
     @Override
     public TimeSampleProvider<? extends HrvSummarySample> getHrvSummarySampleProvider(GBDevice device, DaoSession session) {
-        return new ComputedHrvSummarySampleProvider(getHrvValueSampleProvider(device, session));
+        return new ComputedHrvSummarySampleProvider(getHrvValueSampleProvider(device, session), device, session);
     }
 
     @Override
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/yawell/ring/AbstractYawellRingCoordinator.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/yawell/ring/AbstractYawellRingCoordinator.java
index 9a11451ff2..b951344ef7 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/yawell/ring/AbstractYawellRingCoordinator.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/yawell/ring/AbstractYawellRingCoordinator.java
@@ -179,7 +179,7 @@ public abstract class AbstractYawellRingCoordinator extends AbstractBLEDeviceCoo
 
     @Override
     public TimeSampleProvider<? extends HrvSummarySample> getHrvSummarySampleProvider(GBDevice device, DaoSession session) {
-        return new ComputedHrvSummarySampleProvider(getHrvValueSampleProvider(device, session));
+        return new ComputedHrvSummarySampleProvider(getHrvValueSampleProvider(device, session), device, session);
     }
 
     @Override
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/yawell/ring/samples/ColmiHrvSummarySampleProvider.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/yawell/ring/samples/ColmiHrvSummarySampleProvider.java
deleted file mode 100644
index 89d6ff5219..0000000000
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/yawell/ring/samples/ColmiHrvSummarySampleProvider.java
+++ /dev/null
@@ -1,56 +0,0 @@
-/*  Copyright (C) 2024 Arjan Schrijver
-
-    This file is part of Gadgetbridge.
-
-    Gadgetbridge is free software: you can redistribute it and/or modify
-    it under the terms of the GNU Affero General Public License as published
-    by the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    Gadgetbridge is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU Affero General Public License for more details.
-
-    You should have received a copy of the GNU Affero General Public License
-    along with this program.  If not, see <https://www.gnu.org/licenses/>. */
-package nodomain.freeyourgadget.gadgetbridge.devices.yawell.ring.samples;
-
-import androidx.annotation.NonNull;
-
-import de.greenrobot.dao.AbstractDao;
-import de.greenrobot.dao.Property;
-import nodomain.freeyourgadget.gadgetbridge.devices.AbstractTimeSampleProvider;
-import nodomain.freeyourgadget.gadgetbridge.entities.ColmiHrvSummarySample;
-import nodomain.freeyourgadget.gadgetbridge.entities.ColmiHrvSummarySampleDao;
-import nodomain.freeyourgadget.gadgetbridge.entities.DaoSession;
-import nodomain.freeyourgadget.gadgetbridge.impl.GBDevice;
-
-public class ColmiHrvSummarySampleProvider extends AbstractTimeSampleProvider<ColmiHrvSummarySample> {
-    public ColmiHrvSummarySampleProvider(final GBDevice device, final DaoSession session) {
-        super(device, session);
-    }
-
-    @NonNull
-    @Override
-    public AbstractDao<ColmiHrvSummarySample, ?> getSampleDao() {
-        return getSession().getColmiHrvSummarySampleDao();
-    }
-
-    @NonNull
-    @Override
-    protected Property getTimestampSampleProperty() {
-        return ColmiHrvSummarySampleDao.Properties.Timestamp;
-    }
-
-    @NonNull
-    @Override
-    protected Property getDeviceIdentifierSampleProperty() {
-        return ColmiHrvSummarySampleDao.Properties.DeviceId;
-    }
-
-    @Override
-    public ColmiHrvSummarySample createSample() {
-        return new ColmiHrvSummarySample();
-    }
-}