I just picked up a new Raspberry Pi 4 to play with and spent some time digging around to see if I could disable the status, power and network interface LEDs since I keep the Pi in the same room that I sleep. Here are the directions if you are running a Ubuntu.

Edit:

/boot/firmware/syscfg.txt

And append the following contents

# Disable the PWR LED
dtparam=pwr_led_trigger=none
dtparam=pwr_led_activelow=off
# Disable the Activity LED
dtparam=act_led_trigger=none
dtparam=act_led_activelow=off
# Disable ethernet port LEDs
dtparam=eth_led0=4
dtparam=eth_led1=4

If you are on Raspian, edit:

/boot/config.txt

Instead. After rebooting your Pi should go dark! And you’ll sleep once again in pitch black.