Those thirty seconds at 3am, and why both options are wrong

It is three in the morning and you need the bathroom. You have two choices, and neither of them is good.

The first is to leave the light off. Your eyes do adapt to darkness, but a bathroom rarely has any moonlight in it. The threshold, the bath mat, the water someone dripped an hour ago — none of it is visible. This is the hour when most falls at home happen, and the bathroom is where they happen. Older people are at the sharpest risk, because night vision fades with age and balance is not what it was.

The second is to turn the light on. The switch is usually by the door, so you have to cross the dark room to reach it, which is the risky part in the first place. You find it, you press it, and the ceiling fixture comes on at full output. That brightness was designed for shaving and putting on makeup, not for a two minute visit. Pupils that were wide open in the dark take the full hit, melatonin drops, and you go back to bed to lie there for another twenty minutes.

So the real question is not whether to turn a light on. It is how bright. The answer is far lower than most people expect: around 8%. That is enough to see the floor and the threshold, and not enough for your brain to decide morning has arrived.

Why 8%, rather than just any small number

After a few hours in the dark your eyes are extremely sensitive. A tiny amount of light goes a long way. Keep the level under 10% and your pupils barely have to adjust, so there is none of that stabbing glare. At the same time, push the colour temperature to the warmest end you have. The closer to candlelight, the less blue there is to wake you.

Brightness and colour are two separate things, and plenty of people set the first and assume they are done. A very dim but cold white light will still bring you round. Setting both is what makes it work.

What it actually does during one trip

The same chart, told as a sequence. It makes clearer when the system steps in and when it stays out of the way.

1. 03:11

   You are still in bed

   Nobody is in the bathroom and the light is off. The occupancy sensor reports every few seconds, and the report keeps saying no one. The system is just waiting.

2. 03:12

   You reach the door

   The sensor reports someone. The system checks that this is night, then brings the light up to 8% at the warmest colour it can produce. From your first step inside to the light being on is under a second, so it never feels like waiting.

3. 03:12 to 03:14

   The two minutes you are in there

   As long as the sensor can still see you, nothing changes. It will not decide you left because you stood still, and it will not brighten. You do not have to think about it at all.

4. 03:14

   You walk out

   The sensor reports empty. The system does not kill the light immediately; it waits ninety seconds. That buffer covers your walk back to the bedroom, and it stops a moment of bending down being read as leaving.

5. 03:15 and a half

   The light fades out

   Not a snap to black, but a slow slide down to zero over a few seconds. If you happen to still be awake in bed, the change registers only at the edge of your vision instead of as a sudden drop.

Four things it quietly takes care of

Before and after

What you need to have

Home Assistant treats every device in your home as an entity. The brand and the model do not matter here. What matters is which family it belongs to, and this setup needs very few of them.

How the pieces fit together

There are only three roles here. One watches for people, one decides when the light comes on and when it goes off, and one decides what the light should look like when it does.

Use the ready-made pieces for the middle

The hub ships with a tested set of automation blueprints. Think of a blueprint as a fill-in-the-blanks form: the boxes are already drawn, you only supply the answers. The lead role here is binary_sensor_trigger_light, which exists precisely to do on when someone is there, off when they are not.

Fill those five boxes and the night light is handled. You never have to work out what should happen when somebody stops moving, and you never write a second rule just to switch things off.

Different homes, different numbers

Those are the general values. If your situation is a bit different, adjust from the table below.

Three optional extras

Two blueprints cover the core. The three below are bonuses — add whichever you actually want, and skip the rest without losing anything.

Two modes, each owning half the day

You do not have to set this up yourself

The WOOWTECH hub runs HA-MCP, so the AI can connect straight into your system and do the work, then go back and check that it really runs — rather than handing you a block of settings to paste in.

Prompts you can copy straight out

Each block below can be copied whole, using the button on the right. Pick the one closest to what you want; you do not need all of them.

Set up a night light in my bathroom.
If someone goes in at night, give a little light rather than
full brightness, and let it go out again once they leave.

Set up the night sensor light in my bathroom.
Between 11pm and 6am, as soon as the occupancy sensor sees
someone, bring the light to 8% within a second, at the
warmest colour it can do.
Hold it there while they are still in the room, and do not
switch off just because they stopped moving.
Once they leave, wait 90 seconds, then fade out slowly
instead of cutting the light.
Do not run in daylight, and never override a light I turned
on myself.
If the sensor reports nothing at all for a whole day, send me
a push message to change the battery.
When it is done, test it once yourself, make sure it really
works, then tell me which devices you used.

An older parent lives with us and gets up at night too.
Set the bathroom night light to 15% rather than 8%, and wait
3 minutes after they leave instead of 90 seconds, because
he walks slowly.
If the hallway between the bedroom and the bathroom has a
light as well, treat it the same way.
Test it once yourself before you report back.

The bathroom night light is too dim, I cannot see the floor
properly. Raise it from 8% to 15% and leave everything else
alone. Confirm the current settings back to me afterwards.

I am standing in the bathroom doorway right now, so test it with me on the spot.
I will step inside in a moment. Tell me as it happens whether the sensor picked me up,
what brightness the light was told to use, and what it actually came out at.
If those three numbers do not line up, start from the one that is furthest off.
No need to ask me first, just talk me through it as you go.

Common questions