diff --git a/custom_components/localthings/registry/capabilities/airconditioner.py b/custom_components/localthings/registry/capabilities/airconditioner.py
index d231c52..f4689dc 100644
--- a/custom_components/localthings/registry/capabilities/airconditioner.py
+++ b/custom_components/localthings/registry/capabilities/airconditioner.py
@@ -311,11 +311,14 @@ def _option_switch_write(prefix):
     return write
 
 
-def _option_number_write(prefix):
+def _option_number_write(prefix, factor=1):
+    """Write a numeric options token. `factor` converts the entity's unit into the
+    token's own: good_sleep is offered in hours while the token counts half hours."""
+
     def write(payload, rep, href=None):
         return (
             ["mode", "vs", "0"],
-            {"x.com.samsung.da.options": option_write(prefix, str(round(float(payload))))},
+            {"x.com.samsung.da.options": option_write(prefix, str(round(float(payload) * factor)))},
         )
 
     return write
@@ -528,16 +531,34 @@ CLIMATE = Capability(
             icon="mdi:air-filter",
             entity_category="config",
         ),
-        # "Good Sleep" timer. 0 = off; the upper bound is a guess (only 0 has
-        # been observed on hardware), so a write above 0 is unverified.
+        # "Good Sleep" timer, offered in hours. 0 = off.
+        #
+        # The token counts *half* hours, so it is halved on the way in and doubled
+        # on the way out. The appliance's own app pairs a picker of durations with
+        # the values it puts on the wire, one to one:
+        #
+        #   0:00 0:30 1:00 1:30 2:00 2:30 3:00 4:00 5:00 ... 12:00
+        #      0    1    2    3    4    5    6    8   10  ...    24
+        #
+        # which also pins the maximum at 12 hours (its own help text says so:
+        # "will be turned off after a selected period of time (Max. 12 hours)").
+        # Before this the token was published as if it were hours: the entity
+        # capped at 12, which set six, and twelve hours could not be asked for at
+        # all.
+        #
+        # Half-hour steps are what the app offers below three hours; above that it
+        # offers whole hours only, and a half hour up there is untested rather than
+        # known-bad. A Number cannot change step part-way, and turning this into a
+        # Select of the app's sixteen values would change the entity's domain on
+        # every unit that already has it, so the step stays 0.5 throughout.
         NumberDesc(
             key="good_sleep",
-            rep_fn=_option_token_num("Sleep"),
+            rep_fn=_option_token_num("Sleep", divisor=2),
             exists_fn=_has_option_token("Sleep"),
-            write_fn=_option_number_write("Sleep"),
+            write_fn=_option_number_write("Sleep", factor=2),
             native_min=0,
             native_max=12,
-            step=1,
+            step=0.5,
             unit="h",
             icon="mdi:sleep",
             entity_category="config",
diff --git a/tests/test_airconditioner_artik051_krac.py b/tests/test_airconditioner_artik051_krac.py
index 5738b9e..36723aa 100644
--- a/tests/test_airconditioner_artik051_krac.py
+++ b/tests/test_airconditioner_artik051_krac.py
@@ -217,6 +217,32 @@ def _desc(resources, key):
     return None
 
 
+def test_good_sleep_is_hours_while_the_token_counts_half_hours():
+    """The appliance's own app pairs its duration picker with the values it sends
+    one to one -- 0:30 -> 1, 1:00 -> 2, 3:00 -> 6, 12:00 -> 24 -- so the token is
+    half hours and the entity, which is in hours, has to halve and double. The
+    fixture's own Sleep_0 is the one value that reads the same either way, hence
+    the injected token here."""
+    resources = _load_device(FIXTURE)
+    mode = resources["/mode/vs/0"]
+    mode["x.com.samsung.da.options"] = [
+        option for option in mode["x.com.samsung.da.options"] if option != "Sleep_0"
+    ] + ["Sleep_5"]
+    bound, _ = _discover(resources)
+    assert flatten(bound, resources)["good_sleep"] == 2.5
+
+    desc = _desc(resources, "good_sleep")
+    assert (desc.native_max, desc.step) == (12, 0.5)
+    assert desc.write_fn(2.5, {}) == (
+        ["mode", "vs", "0"],
+        {"x.com.samsung.da.options": ["Sleep_5"]},
+    )
+    # 12 hours is the app's maximum and has to be reachable -- it was not while
+    # the token was published as hours.
+    assert desc.write_fn(12, {})[1]["x.com.samsung.da.options"] == ["Sleep_24"]
+    assert desc.write_fn(0, {})[1]["x.com.samsung.da.options"] == ["Sleep_0"]
+
+
 def test_filter_alarm_time_reads_the_threshold_and_writes_one_token():
     """The interval FilterTime_ is measured against, offered by the app as a
     180/300/500/700 hour radio. All four were walked on hardware while watching