Off My Mind: When Do Superheroes Sleep?

Superheroes dedicate their lives to fighting crime. Crime usually occurs at night so when do the heroes get to sleep? The easy answer would be during the day, right? Batman is sometimes seen crashing in the early hours of the morning and since he doesn't have major commitments as Bruce Wayne, he can snooze all he wants.  Plus, Batman probably knows some secret training techniques that allows him to get fully rested on just a few hours of sleep.  
 
Superman with his super-Kryptonian physiology probably doesn't need much sleep. He gets energy from the sun and probably just sleeps out of habit. He can clearly skip out on a few nights sleep if he's fighting a major super-villain situation.
 
Other heroes actually have day jobs. They're not all billionaires and need a source of income. We've seen Spider-Man crash while trying to juggle his day job (before he was blacklisted as a photographer) along with his criminal-busting activities. Dick Grayson, back when he was a police officer, worked his beat in  Blüdhaven during the day and took to the night as Nightwing afterwards. 
 
The heroes may have superpowers and super physiology, but is this lack of sleep healthy? If they've dedicated themselves to fighting crime and protecting the innocent, who's looking out when they decide to take a nap? 
 == TEASER == 

People enjoy sleeping. Most understand the importance of sleep. Reports suggest that sleep is important to help with learning and memory, controlling weight and metabolism, reducing irritability and developing a healthy immune system. A good superhero knows the importance of keeping their bodies healthy and staying in shape. Their bodies and mind are their main defense against the villains. They would have to understand the importance of sleeping.  
 
If heroes do take the time to get a good amount of sleep, can they truly rest knowing that while they're lying there, crimes are being committed and innocents are being threatened? It could come down to how dedicated and focused are they in vanquishing evil. It would help if they developed some sort of schedule with other heroes with shifts to cover different hot spots for crime. I don't really recall seeing Batman ask someone to cover his shift while he catches some z's. Spider-Man often worked alone and didn't have anyone he could ask to take his place.  
 

Do heroes deserve time to sleep? They often make huge sacrifices in fighting crime but that's always been their decision. Where should they draw the line between personal sacrifice and protecting the innocent? If someone is harmed moments after a hero goes home for some sleep, should they feel guilty about it? Do heroes change into pajamas or do they keep on their super-suits in case they need to dash out on a moments notice? Perhaps there are some questions we'll never get answered.