December 01, 2025

Turn on lights when motion is detected

Automatically turning on lights when motion is detected is one of the most popular and useful smart home automations. It solves the everyday problem of fumbling for light switches in the dark and creates a seamless, effortless lighting experience.

Use cases

Indoor automation

Nighttime navigation - Bathroom lights turn on at low brightness when you get up at night
Home office - Lights automatically turn on when you enter your workspace
Hallways - Lights turn on as you move through the house
Closets - No more fumbling for switches in dark spaces

Outdoor Automation

Garden Shed - Motion sensor triggers light when you enter
Porch Light - Automatically lights up for guests and delivery drivers

Products needed

Essential Equipment

Motion Sensor

Popular brands: Philips Hue, Aqara, SmartThings, Wyze
Indoor: Standard motion sensors • Outdoor: Weatherproof IP65+ rated sensors

Smart Light Switch or Bulb

Switches: Lutron, GE, Inovelli, Leviton
Bulbs: Philips Hue, LIFX, Wyze, Sengled

💡 Outdoor Motion Sensing Tip

Use sensors specifically rated for outdoor use (IP65 or higher)
OR protect indoor sensors with weatherproof enclosures
OR place sensors under eaves to avoid direct water exposure

Basic automation setup

IF motion detected THEN turn on lights to 100%

🌞 Day vs. Night Dimming Enhancement

Daytime: Brightness 100% OR skip turning on if room has natural light (use lux sensor)
Nighttime (9 PM - 11 PM): Medium brightness 50%
Deep Night (11 PM - 6 AM): Low brightness 10-20% with warm color temperature
Early Morning (6 AM - 9 AM): Full brightness 100%

Triggers

Motion detected by sensor

Conditions

Time-based: Different behavior for day vs. night
Lux sensor: Only activate if room is dark (below certain lux level)
Home mode: Only when home is occupied

Actions

Turn on light switch or bulb
Set to preferred brightness level (dimming percentage)

Platform-specific examples

Home Assistant

Trigger Motion sensor state changes to "on"

Condition Light level (lux) is below 100

Action Turn on bathroom light

Night (10 PM - 6 AM): Set brightness to 10%

Day (6 AM - 10 PM): Set brightness to 100%

SmartThings

IF Motion is detected on sensor

AND Time is between 10 PM and 6 AM

THEN Turn on light to 10%

Note: Create second routine for daytime with 100% brightness

Hubitat

Trigger Motion sensor active

Condition Mode is "Night" or time between 10 PM - 6 AM

Action Set light to 10%

Setup: Use Rule Machine or Simple Automation Rules
Note: Create separate rule for daytime at 100%

Apple HomeKit

When Motion sensor detects motion

Time Between 10 PM and 6 AM

Do Turn on bathroom light at 10%

Note: Repeat for daytime hours at 100%

Alexa

When Motion sensor detects motion

Condition Between 10 PM and 6 AM

Action Turn on light to 10%

Note: Create second routine for daytime with 100% brightness

Google Home

When Motion sensor detects motion

Condition Time between 10 PM - 6 AM

Action Set light to 10%

Note: Create second routine for daytime with 100% brightness

Advanced features

Multiple brightness levels

Create different levels throughout the night:

9 PM - 11 PM 30% Still awake, need moderate light

11 PM - 5 AM 10% Minimal disturbance

5 AM - 7 AM 20% Gentle wake-up

7 AM - 9 PM 100% Full brightness

Lux-based activation

Only turn on lights if the room is actually dark:

Add a condition that light level must be below a certain threshold (e.g., 100 lux)
This prevents lights from turning on during daytime when natural light is sufficient

Zone-based motion

For larger rooms, use multiple motion sensors to track which area someone is in and only light that zone.

Common issues and solutions

Lights turn on too slowly

Problem: Delay between motion detection and lights turning on causes you to reach for the switch.

Solutions:

Check sensor placement - should detect motion before entering room
Reduce automation processing time - use local control instead of cloud
Use faster communication protocols (Zigbee/Z-Wave vs WiFi)
Optimize automation logic to minimize conditions

Lights turn on when not needed

Problem: Lights activate from pets, sunlight reflections, or other false triggers.

Solutions:

Adjust motion sensor sensitivity
Add lux sensor condition to prevent daytime activation
Use pet-immune motion sensors
Position sensor away from windows and heat sources
Add time-based conditions

Inconsistent performance

Problem: Sometimes works, sometimes doesn't.

Solutions:

Check sensor battery levels
Verify wireless signal strength (Zigbee/Z-Wave mesh)
Replace batteries before completely dead
Add repeaters/extenders for distant sensors
Check for interference from other devices

Sensor placement best practices

Height

Optimal: 6-8 feet high for best coverage
Corners: Good for monitoring entire room
Entry points: Near doors for immediate detection

Angle

Ceiling mount: Wide coverage, detects all motion
Wall mount: Directional, catches people entering
Corner mount: 90° coverage, good for hallways

Coverage testing

Mount sensor temporarily with tape
Walk through room at different paths
Verify all entry points are covered
Check for dead zones
Adjust position or add additional sensors
Permanently mount once confirmed

What to avoid

Near windows - Sunlight and outdoor motion cause false triggers
Near heating/AC vents - Temperature changes trigger sensors
Pointed at moving objects - Ceiling fans, curtains, pets
Behind furniture - Blocks detection zone

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