How to make a day and night cycle in Roblox Studio

How time of day works in Roblox

The Lighting service holds the time of day in two linked properties: ClockTime, a number of hours, and TimeOfDay, the same time as text like "14:30:00". Change one and the other follows, and the sun, moon, sky colour and shadows move to match. Roblox's Lighting reference notes that it does not track real time and only changes when a script changes it.

Step 1: Turn the clock

Insert a Script in ServerScriptService named DayNightCycle:

-- Script in ServerScriptService named DayNightCycle.
-- Runs a full day in DAY_MINUTES real minutes. Lighting changes reach every player.
local Lighting = game:GetService("Lighting")
local RunService = game:GetService("RunService")

local DAY_MINUTES = 10 -- real minutes for one whole day and night
local START_HOUR = 8 -- the time of day when the server starts (0 to 24)

local hoursPerSecond = 24 / (DAY_MINUTES * 60)
Lighting.ClockTime = START_HOUR

RunService.Heartbeat:Connect(function(deltaTime: number)
	Lighting.ClockTime = (Lighting.ClockTime + deltaTime * hoursPerSecond) % 24
end)

A day is 24 hours of game time in DAY_MINUTES * 60 real seconds, so each real second adds 24 / (DAY_MINUTES * 60) hours: 0.04 with the default 10 minutes. Heartbeat passes the seconds since the last frame, so the sum stays right however fast the server runs. The % 24 wraps midnight back to 0.

Step 2: Street lights that turn on at night

1. Make a lamp: a part for the bulb with a PointLight or SpotLight inside it.
2. Tag the bulb part StreetLight in the Properties window, under Tags. A tagged Model works too: every light inside it switches.
3. Insert a second Script in ServerScriptService named StreetLights:

-- Script in ServerScriptService named StreetLights.
-- Turns on every light inside parts tagged "StreetLight" at night, and off by day.
local CollectionService = game:GetService("CollectionService")
local Lighting = game:GetService("Lighting")

local LIGHTS_ON_HOUR = 18 -- 6 pm
local LIGHTS_OFF_HOUR = 6.5 -- 6:30 am

local function isNight(): boolean
	local hour = Lighting.ClockTime
	return hour >= LIGHTS_ON_HOUR or hour < LIGHTS_OFF_HOUR
end

local function setLamp(lamp: Instance, on: boolean)
	for _, child in lamp:GetDescendants() do
		if child:IsA("Light") then
			child.Enabled = on
		end
	end
	if lamp:IsA("BasePart") then
		lamp.Material = if on then Enum.Material.Neon else Enum.Material.SmoothPlastic
	end
end

local lightsOn: boolean? = nil
local function update()
	local night = isNight()
	if night == lightsOn then
		return -- nothing changed since the last check
	end
	lightsOn = night
	for _, lamp in CollectionService:GetTagged("StreetLight") do
		setLamp(lamp, night)
	end
end

Lighting:GetPropertyChangedSignal("ClockTime"):Connect(update)
CollectionService:GetInstanceAddedSignal("StreetLight"):Connect(function(lamp: Instance)
	setLamp(lamp, isNight())
end)
update()

GetPropertyChangedSignal("ClockTime") fires every time the cycle moves the clock, which is every frame. The script only works out whether it is night and returns straight away unless that answer changed, so the lamps are touched twice a day, not 60 times a second. A bulb part also switches to Neon, so it glows.

Going further: night mood and a clock on screen

• Darker nights: in the same Heartbeat, lower Lighting.Brightness or change Lighting.OutdoorAmbient when ClockTime is after 18 or before 6.
• A clock in the corner: a LocalScript can show Lighting.TimeOfDay, which is already formatted as text, in a TextLabel and update it on GetPropertyChangedSignal("TimeOfDay").
• Night events: the same day or night check can start a round or spawn night-only NPCs.

Test it

1. Set DAY_MINUTES to 1 so you can watch a whole day.
2. Press Play. The sun crosses the sky, the sky darkens and the street lights switch on at 6 pm.
3. Select Lighting in the Explorer during the test (on the Server view) and watch ClockTime count up.
4. Set DAY_MINUTES back before you publish.

Common errors and fixes

If the sun does not move, check the Output window for a red line first.

Build it with RoCode

If you would rather not set this up by hand, RoCode can build it in the place you have open. RoCode is an independent AI agent for Roblox Studio, not made by Roblox: you describe the change in a web chat, and its Studio plugin creates the scripts and objects in your Explorer.

RoCode can also build themed world islands (volcano, canyon, jungle and snow) in one call, which pair well with a day and night cycle. You still watch a full day in a playtest to judge the mood. How RoCode connects to Studio.

Questions

Sources and further reading

• Roblox Creator Docs: Lighting. ClockTime, TimeOfDay, Brightness and ambient colours
• Roblox Creator Docs: RunService. Heartbeat and deltaTime
• Roblox Creator Docs: Lighting (environment). how global lighting looks at each time
• Roblox Creator Docs: CollectionService. tags for the street lights

How the code was checked: every script on this page passes Luau's strict type checker against Roblox's API definitions (luau-lsp, 23 October 2026). A type check catches misspelt APIs and wrong types, not game logic, so playtest in Studio before you publish.