diff --git a/.vscode/settings.json b/.vscode/settings.json
index 3503ee7..7808894 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -6,5 +6,6 @@
     },
     "sweetpad.xcodebuildserver.serverEnv": {
         "DEVELOPER_DIR": "/Applications/Xcode.app/Contents/Developer"
-    }
+    },
+    "diffEditor.ignoreTrimWhitespace": true
 }
diff --git a/Bedtime/Bedtime/Constants.swift b/Bedtime/Bedtime/Constants.swift
index ba9082d..945e4e9 100644
--- a/Bedtime/Bedtime/Constants.swift
+++ b/Bedtime/Bedtime/Constants.swift
@@ -9,4 +9,5 @@ import Foundation
 
 class Constants {
     static let iconWidth: CGFloat = 30
+    static let sleepHistoryDays = 30
 }
diff --git a/Bedtime/Bedtime/Models/HealthKitManager.swift b/Bedtime/Bedtime/Models/HealthKitManager.swift
index ebad451..9889942 100644
--- a/Bedtime/Bedtime/Models/HealthKitManager.swift
+++ b/Bedtime/Bedtime/Models/HealthKitManager.swift
@@ -83,7 +83,11 @@ class HealthKitManager: ObservableObject {
     private func fetchSleepDataForDisplay() async throws {
         let calendar = Calendar.current
         let endDate = Date()
-        guard let startDate = calendar.date(byAdding: .day, value: -30, to: endDate) else {
+        let today = calendar.startOfDay(for: endDate)
+        // Fetch one extra day before the UI range: grouping (midpoint + 6h) can assign
+        // sessions that start the previous evening to the oldest displayed day, including
+        // short blocks (e.g. 9–11pm) as well as overnight sleep.
+        guard let startDate = calendar.date(byAdding: .day, value: -Constants.sleepHistoryDays, to: today) else {
             throw NSError(domain: "HealthKitManager", code: 1, userInfo: [NSLocalizedDescriptionKey: "Failed to calculate start date"])
         }
         
diff --git a/Bedtime/Bedtime/Views/Components/SleepDayGroup.swift b/Bedtime/Bedtime/Views/Components/SleepDayGroup.swift
index ce2a9cf..d306609 100644
--- a/Bedtime/Bedtime/Views/Components/SleepDayGroup.swift
+++ b/Bedtime/Bedtime/Views/Components/SleepDayGroup.swift
@@ -33,6 +33,10 @@ struct SleepDayGroup: View {
         return (abs(difference), difference >= 0, color)
     }
     
+    private var hasSessions: Bool {
+        !sessions.isEmpty
+    }
+    
     var body: some View {
         VStack(spacing: 0) {
             // Day header (always visible)
@@ -43,41 +47,52 @@ struct SleepDayGroup: View {
                             .font(.subheadline)
                             .fontWeight(.medium)
                         
-                        Text("\(timeFormatter.string(from: sessions.last?.startDate ?? Date())) - \(timeFormatter.string(from: sessions.first?.endDate ?? Date()))")
-                            .font(.caption)
-                            .foregroundColor(.secondary)
+                        if hasSessions {
+                            Text("\(timeFormatter.string(from: sessions.last!.startDate)) - \(timeFormatter.string(from: sessions.first!.endDate))")
+                                .font(.caption)
+                                .foregroundColor(.secondary)
+                        } else {
+                            Text("No sleep data")
+                                .font(.caption)
+                                .foregroundColor(.secondary)
+                        }
                     }
                     
                     Spacer()
                     
                     VStack(alignment: .trailing, spacing: 2) {
-                        Text(TimeFormatter.formatDuration(sessions.reduce(0) { $0 + $1.duration }))
-                            .font(.subheadline)
-                            .fontWeight(.semibold)
-                            .foregroundColor(.primary)
-                        
-                        HStack(spacing: 2) {
-                            Text(balanceImpact.isPositive ? "+" : "-")
-                                .font(.caption)
-                                .foregroundColor(balanceImpact.color)
+                        if hasSessions {
+                            Text(TimeFormatter.formatDuration(sessions.reduce(0) { $0 + $1.duration }))
+                                .font(.subheadline)
+                                .fontWeight(.semibold)
+                                .foregroundColor(.primary)
                             
-                            Text(String(format: "%.1fh", balanceImpact.value))
-                                .font(.caption)
-                                .foregroundColor(balanceImpact.color)
+                            HStack(spacing: 2) {
+                                Text(balanceImpact.isPositive ? "+" : "-")
+                                    .font(.caption)
+                                    .foregroundColor(balanceImpact.color)
+                                
+                                Text(String(format: "%.1fh", balanceImpact.value))
+                                    .font(.caption)
+                                    .foregroundColor(balanceImpact.color)
+                            }
                         }
                     }
                     
-                    Image(systemName: isExpanded ? "chevron.up" : "chevron.down")
-                        .font(.caption)
-                        .foregroundColor(.secondary)
+                    if hasSessions {
+                        Image(systemName: isExpanded ? "chevron.up" : "chevron.down")
+                            .font(.caption)
+                            .foregroundColor(.secondary)
+                    }
                 }
                 .padding(.vertical, 8)
                 .contentShape(Rectangle())
             }
             .buttonStyle(PlainButtonStyle())
+            .disabled(!hasSessions)
             
             // Session details (expandable)
-            if isExpanded {
+            if isExpanded && hasSessions {
                 VStack(spacing: 4) {
                     ForEach(Array(sessions.enumerated()), id: \.offset) { index, session in
                         SleepSessionRow(session: session)
diff --git a/Bedtime/Bedtime/Views/RecentSleepSessionsCard.swift b/Bedtime/Bedtime/Views/RecentSleepSessionsCard.swift
index e061641..aad860f 100644
--- a/Bedtime/Bedtime/Views/RecentSleepSessionsCard.swift
+++ b/Bedtime/Bedtime/Views/RecentSleepSessionsCard.swift
@@ -9,10 +9,17 @@ import SwiftUI
 
 struct RecentSleepSessionsCard: View {
     
-    init(sessions: [Date: [SleepSession]], sleepGoal: Double) {
+    init(sessions: [Date: [SleepSession]], sleepGoal: Double, dayCount: Int = Constants.sleepHistoryDays) {
         self.sessions = sessions
-        self.sortedSessions = sessions.sorted { $0.key > $1.key }
         self.sleepGoal = sleepGoal
+        
+        let calendar = Calendar.current
+        let today = calendar.startOfDay(for: Date())
+        self.sortedSessions = (0..<dayCount).compactMap { offset -> (Date, [SleepSession])? in
+            guard let day = calendar.date(byAdding: .day, value: -offset, to: today) else { return nil }
+            let dayStart = calendar.startOfDay(for: day)
+            return (dayStart, sessions[dayStart] ?? [])
+        }
     }
     
     let sessions: [Date: [SleepSession]]