Just got the unit and I’ve noticed that the AQI goes from 1-5 during the day to over 160 after sun down. This of course causes the unit to go into the highest fan setting which is super loud. The AQI never drops down either, It’s like the purifier can’t lower the the AQI at this level, only sustain it. Then after sunrise it drops and continues to do so throughout the day.
Anyone else get this behavior?
This is actually really normal, and not a bug.
There is a ton of data on why AQI is always worst at night and early morning in general everywhere.
The short answer is because during the day the sun warms up the air and causes everything to rise, taking away a lot of the polluted air from where we live and breathe. The opposite happens at night though…the temperature drops which causes the atmosphere to trap car emissions, CO2, and other pollutants in your house, etc and this cold air pushes them all close together and down where we live and breathe. There are often a lot of trucks and such on the roads at night and their pollution gets kept down here instead of rising up. This becomes a bigger problem when the house is not properly ventilated.
Honestly, this is one of the reasons I have been strongly advocating for Wyze to allow us to turn off the LED display without putting the Air Purifier into Sleep Mode. Sleep Mode is the only way to turn off the display right now, but it forces the AP to stay on low fan speed during the hours we may most need it to be going to the higher settings when the air is actually the worst. I would like to be able to leave it on Auto and still turn off the display, that way when this natural WORST AQI TIME hits and the AP is most needed to clean the air, it can do so without broadcasting a bright screen. Wyze is working to release an update for this BTW, so it is coming.
Anyway, the answer is “Science”…we most need air purifiers at night time because that is when our air is the worst.
Could it be something with lighting (since it uses a laser) or your HVAC?
Do you turn your HVAC fan off at night, and what happens if you leave it on?
What happens if you leave a light on and see if that effects it?
Or that. Looks like your the pro here, not me 
That makes total sense, learned something new! 