Whenever I restart my computer the monitor is a fairly bright white, but then within a few seconds it kind of dulls to what I see as a kind of beige colour. The PC is a Lenovo All-In-One about 3 years old. I can't find anything in the set up to change this. Is this normal as being less tiring on the eyes?

My ASUS had a nightlight feature which does the same as you describe.  At least on mine It is easy to turn on and off.  It is sometimes also called a blue light filter.  Have a google and you'll see quite some suggestions, e.g.

 

Here's how to activate it.

1. Open the Start Menu.
2. Click the gear icon to bring up the Settings Menu.
3. Choose System.
4. Select Display.
5. Toggle the Night light switch to On.
6. Click Night light settings to adjust the level of blue displayed, or determine the time for Night Light to activate automatically.

On your start menu list of programs look under Lenovo for Dynamic Brightness System - that might be set to turn on each time computer starts.  I don't use so not sure of effect.

2 hours ago, Upnotover said:

My ASUS had a nightlight feature which does the same as you describe.  At least on mine It is easy to turn on and off.  It is sometimes also called a blue light filter.  Have a google and you'll see quite some suggestions, e.g.

 

Here's how to activate it.

1. Open the Start Menu.
2. Click the gear icon to bring up the Settings Menu.
3. Choose System.
4. Select Display.
5. Toggle the Night light switch to On.
6. Click Night light settings to adjust the level of blue displayed, or determine the time for Night Light to activate automatically.

No, the night light is always off.

1 minute ago, giddyup said:

No, the night light is always off.

Check this...

https://forums.lenovo.com/t5/Lenovo-IdeaPad-1xx-3xx-5xx-7xx-Edge-LaVie-Z-Flex-Notebooks/Night-light-turns-on-randomly/m-p/4421564?page=1

ime, 3 years is about the expire rate of monitors,

i sit with the computer a lot though

8 minutes ago, scammed said:

ime, 3 years is about the expire rate of monitors,

i sit with the computer a lot though

Well my Lenovo AIO has been running about 13 hours a day for nine years now and no issues with the monitor.

Just now, lopburi3 said:

Well my Lenovo AIO has been running about 13 hours a day for nine years now and no issues with the monitor.

i presume it goes back and idle for most of that time

20 minutes ago, scammed said:

i presume it goes back and idle for most of that time

That would not be a valid assumption however.  I use most of the time either as computer or video screen.

Not only Leovo but also windows has this option.

Have it set that the screen turns amberish around 18.40 filtering out the blue.

 

 

Go to settings (right-click with the mouse on that 'night light' square) and check if it was (accidentally) turned on.

9 minutes ago, lopburi3 said:

That would not be a valid assumption however.  I use most of the time either as computer or video screen.

ok, my screens, on laptop and external, tend to have an average of 3 years of good quality,

but i do use them more then most people

20 hours ago, giddyup said:

Whenever I restart my computer the monitor is a fairly bright white, but then within a few seconds it kind of dulls to what I see as a kind of beige colour. The PC is a Lenovo All-In-One about 3 years old. I can't find anything in the set up to change this. Is this normal as being less tiring on the eyes?

I can recall this from the tube monitors, but in your case which is an AIO I should first look on the software side.

 

Can you, when turn on the computer, going to the system settings (BIOS) by pressing F1 when the Lenovo logo is showing

( some computers has other keys; F2/DEL/F10..)

 

Once in the BIOS, just wait.. do you see the screen turning dull?

 

If yes, then it is likely an hardware issue and not a software setting.

4 minutes ago, scammed said:

ok, my screens, on laptop and external, tend to have an average of 3 years of good quality,

but i do use them more then most people

Having screens here, powered on for a long time and some screens are from 2009.

Only have one screen turning dull but not only that it also lost brightness in the corners.

 

There are two different lightsources with them, fluor and led.

The one that went dull is a fluor tube screen, and have another screen in the bit box that has a dull grey-isch spot which is a led screen with one of the led dying,