If you suspect that Joe Biden is suffering from dementia and that the very common symptoms known as "sundowning" are part of his illness, then his "mystifying" campaign schedule starts to make sense.

The schedule that "mystified" National Review a few days ago:

As of late, Biden's team has regularly put a "lid" on his day by noon — or even earlier. And, when it does not, the events that Biden attends seem to have been designed to be either easily cancelable or easily replaceable.

The lid has been placed on his schedule earlier in recent days, and yesterday, it attracted mockery by President Trump.

President Trump mocked Joe Biden on Thursday after the Democratic presidential nominee's campaign called a "lid" on activities for the day early in the morning, saying Biden would be preparing for Tuesday night's debate. 

Trump, whose campaign has ripped Biden for not doing more press events while seeking to raise questions about the Democrat's age, stamina and mental acumen, called Biden "sleepy" and "low energy," insults he has repeatedly hurled, 

"Sleepy Joe Biden just closed down his campaign for the day (Again)," Trump tweeted. "Wants to rest! He is a very LOW ENERGY INDIVIDUAL, and our Country cannot make it in these exciting, but complex and competitive times, with a Low Energy President !!!" 

AARP lists the symptoms of sundowning:

• mood swings
• anxiety
• sadness
• restlessness
• energy surges
• increased confusion
• hallucinations
• delusions

I don't think the "lid" is mysterious at all.  The explanation that best satisfies the observable data is that Biden is systematically shifting his circadian rhythms so his body will behave as if it were 9 A.M. or so when the clock in Cleveland, where the debate will be held, reads 9 P.M.  I've done it myself, because at times in my past career as a consultant, I have had to travel between the U.S. and Asia and arrive ready to function at high levels on local time, overcoming an 11-hour time difference between the East Coast and Japan.  There was a thankfully relatively short period of time when I was making that trip every three or four weeks.

The Sleep Foundation explains how to shift your body's clock:

To adjust your sleep hours, the biggest tool at your disposal is light (or lack thereof). When it's dark outside, your brain naturally signals to your body to release melatonin, a hormone that makes you feel sleepy. When it's light outside, your brain sends a signal to cut off the melatonin supply, making you feel more awake.  To shift your circadian rhythm earlier, dim the lights in your home an hour before bedtime to prepare yourself for sleep. As soon as the alarm goes off, turn on as many lights as you can to simulate a bright sunny morning.

Other Strategies

Your circadian rhythm responds well to light cues, but other aspects of your daily life can influence it as well. For instance, the time of day you eat can speed up or delay your internal clock. If you shift your breakfasts, lunches, and dinners to later in the day, this may also move your body's internal clock back, making a later bedtime feel more natural. Another variable: Your exercise routine. Hitting the gym in the evening instead of the morning can shift your circadian rhythm later as well.

Whatever strategy you follow, it's best to make the changes in small increments. Move your plans 15 minutes earlier or later each day until your find a rhythm that works for you.

I found that I could shift about one hour a day in my sleep rhythm.  That would mean Biden has needed at least 12 days to be ready to go at 9 P.M. Eastern as if he had woken up, bathed and breakfasted, and was ready to start a workday at 9 A.M.  Because his campaign has the resources to obtain lights that precisely duplicate sunlight and maintain absolute control over stimuli (no phone calls or other distractions when it is supposed to be nighttime at noon), Joe's efforts have a high probability of success.

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