Donald Trump has a contentious relationship with sleep, and frequently boasts about sleeping just three or four hours a night.
"How does somebody that's sleeping 12 and 14 hours a day compete with someone that's sleeping three or four?" he once said, according to the Daily News.
However, many political commentators -- including Timothy Egan in The New York Times and the hosts of "Morning Joe" -- have suggested that Trump's resistance to getting a full night's sleep could help explain his erratic behavior.
The latest example of his "sleep-baiting" happened on Thursday, when the presumptive Republican nominee trashed Democratic candidate Hillary Clinton by comparing her speeches to a sleep aid.
"To watch her is like Sominex ... you sleep all night," he said at a rally in San Jose, California, taking a jab at a speech about national security Clinton had delivered earlier that day.
Sominex is an over-the-counter antihistamine widely used to treat insomnia and jet lag.
"I think she could make more money if she made speeches and sold them to people that can't sleep," Trump added. He also called her "unpresidential" and "hard to watch."
Trump's insult was a curiously anodyne attack on a speech that was widely praised both for its message and criticisms of the GOP candidate.
However, Clinton, who The Associated Press says has clinched enough delegates to win the Democratic nomination, may not be sleeping much more. She "often gets no more than four or five" hours of sleep a night, Rebecca Traister wrote in a recent New York magazine profile of the candidate.
Editor’s note: Donald Trump is a serial liar, rampant xenophobe, racist, misogynist, birther and bully who has repeatedly pledged to ban all Muslims — 1.6 billion members of an entire religion — from entering the U.S.