[exfatloss]

I think it's pretty normal not to be "on" 24/7. We run on a circadian rhythm that is diurnal, i.e. has two cycles per day. Most people peak once some time in the late morning and then once again in the late afternoon.

Depending on your chronotype, this might be shifted - a super night owl would probably experience both of them later. E.g. I usually peak late at night, maybe between 8pm and midnight.

These cycles are measurable in things like nervous system, core body temperature, and so on. So it's no surprise that your brain isn't "always on." Nobody's brain is.

You could try finding your peak times and structuring your day around them so you can make maximal use of them.