diff --git a/reports/graphs.py b/reports/graphs.py
index 754ed3da..27e888d9 100644
--- a/reports/graphs.py
+++ b/reports/graphs.py
@@ -5,13 +5,14 @@ from collections import OrderedDict
 
 from django.db.models import Count, Case, When
 from django.db.models.functions import TruncDate
-from django.utils import timezone, duration
+from django.utils import timezone
 
 import pandas as pd
 import plotly.offline as plotly
 import plotly.graph_objs as go
 
 from core.models import DiaperChange, Sleep
+from core.utils import duration_string
 
 from .utils import default_graph_layout_options, split_graph_output
 
@@ -58,49 +59,81 @@ def diaperchange_types(child):
 
 
 def sleep_times(child):
-    # TODO: Handle dates crossing over midnight!
+    """Create a graph showing blocked out period of sleep during each day."""
     instances = Sleep.objects.filter(child=child).order_by('start')
     y_df = pd.DataFrame()
     text_df = pd.DataFrame()
     last_end_time = None
+    adjustment = None
     df_index = 0
     for instance in instances:
         start_time = timezone.localtime(instance.start)
         end_time = timezone.localtime(instance.end)
         start_date = start_time.date().isoformat()
+        duration = instance.duration
+
+        # Check if the previous entry crossed midnight (see below).
+        if adjustment:
+            # Fake (0) entry to keep the color switching logic working.
+            df_index = _add_sleep_entry(
+                y_df, text_df, 0, adjustment['column'], 0)
+            # Real adjustment entry.
+            df_index = _add_sleep_entry(
+                y_df,
+                text_df,
+                df_index,
+                adjustment['column'],
+                adjustment['duration'],
+                'Asleep {} ({} to {})'.format(
+                    duration_string(duration),
+                    adjustment['start_time'].strftime('%I:%M %p'),
+                    adjustment['end_time'].strftime('%I:%M %p')
+                )
+            )
+            last_end_time = timezone.localtime(adjustment['end_time'])
+            adjustment = None
+
+        # If the dates do not match, set up an adjustment for the next day.
+        if end_time.date() != start_time.date():
+            adj_start_time = end_time.replace(hour=0, minute=0, second=0)
+            adjustment = {
+                'column': end_time.date().isoformat(),
+                'start_time': adj_start_time,
+                'end_time': end_time,
+                'duration': (end_time - adj_start_time).seconds/60
+            }
+
+            # Adjust end_time for the current entry.
+            end_time = end_time.replace(
+                day=start_time.day, hour=23, minute=59, second=0)
+            duration = end_time - start_time
+
         if start_date not in y_df:
-            y_df.assign(**{start_date: 0 in range(0, len(y_df.index))})
-            text_df.assign(**{start_date: 0 in range(0, len(y_df.index))})
             last_end_time = start_time.replace(hour=0, minute=0, second=0)
-            df_index = 0
 
         # Awake time.
-        y_df.set_value(
-            df_index, start_date, (start_time - last_end_time).seconds/60,
-        )
-        text_df.set_value(
+        df_index = _add_sleep_entry(
+            y_df,
+            text_df,
             df_index,
             start_date,
-            'Awake for from {} to {} ({})'.format(
-                last_end_time.strftime('%I:%M %p'),
-                start_time.strftime('%I:%M %p'),
-                duration.duration_string(start_time - last_end_time)
-            )
+            (start_time - last_end_time).seconds/60
         )
-        df_index += 1
 
         # Asleep time.
-        y_df.set_value(df_index, start_date, instance.duration.seconds/60)
-        text_df.set_value(
+        df_index = _add_sleep_entry(
+            y_df,
+            text_df,
             df_index,
             start_date,
-            'Asleep for from {} to {} ({})'.format(
+            duration.seconds/60,
+            'Asleep {} ({} to {})'.format(
+                duration_string(duration),
                 start_time.strftime('%I:%M %p'),
-                end_time.strftime('%I:%M %p'),
-                duration.duration_string(instance.duration)
+                end_time.strftime('%I:%M %p')
             )
         )
-        df_index += 1
+
         last_end_time = end_time
 
     dates = list(y_df)
@@ -151,3 +184,16 @@ def sleep_times(child):
     })
     output = plotly.plot(fig, output_type='div', include_plotlyjs=False)
     return split_graph_output(output)
+
+
+def _add_sleep_entry(y_df, text_df, index, column, duration, text=''):
+    """Create a duration and text description entry in a DataFrame and return
+    the next index on success."""
+    if column not in y_df:
+        y_df.assign(**{column: 0 in range(0, len(y_df.index))})
+        text_df.assign(**{column: 0 in range(0, len(text_df.index))})
+        index = 0
+
+    y_df.set_value(index, column, duration)
+    text_df.set_value(index, column, text)
+    return index + 1