Four o'clock Meltdown/ Breakdown/ Collapse

so true dear Iain, most meds create secondary maladies.

I wake everyday at 4. I let that be my base rhythm.

I have noticed one factor that will drive me to the couch at 4 pm:

Eating a meal with a challenging diet, especially meat and gluten. If I avoid them I feel energized after a meal.

I also have an antibiotic resistant, persistent bacterial infection that, when it flares, mimics a flu and I have no energy.

Beneficial gut bacteria and enzymes out of balance may also be a factor.

Diet is all important to me.

Note how you feel after and when you eat. You will find the right foods for you and they will give you all the energy you crave.

Robert124 said:

During the day at 4pm I often lose consciousness and fall asleep

From the regularity I can think of 2 causes:

1 - your Circadian rhythm is in need of a rebalance. This is the mechanism that helps people fall asleep at the same time at night. More info on it here: https://en.wikipedia.org/wiki/Circadian_rhythm

Possibly getting your GP to refer you to a sleep specialist will work if you cannot work out how to do it yourself.

2 - are you on medication that you take at the same time daily? This could cause the effect if it hits your bloodstream at about these times. If it is the case then speak to your GP about adjusting the dose / frequency or active ingredients.

That is how I would approach it.