If you look more like an extra from The Walking Dead than your usual self, it might be time to change your sleep habits.
Dr W Chris Winter told ABC Radio Adelaide's Mornings program one of the first things people needed to do if they felt like death warmed up was to figure out whether they were sleepy or fatigued.
Sleepy was simply defined as having trouble staying awake.
Fatigue, according the Dr Winter, was more a physical feeling of tiredness.
"It is important to define them, as often when people feel fatigued they make the mistake of going to bed," he said.
"When you feel fatigued or tired, rest. When you feel sleepy, go to bed."
Dr Winter said there was an ongoing conversation by many that they were not able to sleep.
"You are about as likely not to be able to sleep as you are not to be able to eat or drink water."
But my partner snores
He said if your partner's nocturnal habits were so bad that it was affecting your sleep, it was time to take action.
"The best way is to convince your partner that there are things that can be done about snoring.
"In some cases snoring can indicate fairly serious sleep conditions that can have really negative health consequences."
But if the snoring was light or irregular, ear plugs or sleeping in separate rooms worked.
"Create some sort of schedule and say, 'Look, for my own health and my own sanity, I'm going to sleep in a separate bedroom on Tuesday and Thursday nights'," Dr Winter recommended.
Napping may not always help
Dr Winter said he told patients to think about napping the same way they would think about snacking.
"If you have a big snack it will most likely affect your [appetite for] dinner.
"Napping is most appropriate when something is preventing you from getting your full night of sleep, such as travelling."
Falling asleep anywhere may not be good
We all know one person who can sleep on planes, in buses, in a car — anytime, anywhere.
Although it might seem great to be able to do it, Dr Winter said it could highlight underlying problems.
"It could be that something is going on in their life that means they are needing more sleep than normal — like training for a marathon," he said.
"If everything is the same ... I would look at something being intrinsically wrong with their sleep and maybe getting a sleep study to make sure everything is OK."
Keep a routine
Dr Winter said it was important, when possible, to keep your wake and sleep hours regular.
He said even the regularity with which you wake up was important.
"You really want to make that as consistent as possible, even after nights when you might have stayed up a little later.
"You can always make up for those with a nap if you need to."