Stores opened at 6 a.m. on the Friday morning after Thanksgiving. Sure, you spent the whole night in a tent outside, but at least you closed your eyes. Now, big chains like Target, Kohl’s, and Best Buy open at midnight. That’s six extra hours of selling time. What does a dedicated shopper need to do other than stay awake all night?

About 152 million people are expected for shopping during Black Friday weekend, according to the National Retail Federation. That’s 152 million people who might be feeling a bit exhausted, not to mention the thousands of employees who work this weekend, including those who work nights.

Anytime you disturb your body’s natural circadian rhythm, there will be consequences. The first thing to do is your mood, says Lisa Shives, CNN sleep expert. You will be irritable and impatient, making the mall a perfect storm of stress. The next step is your metabolism – so stay away from the food court.

“A lot of the hormones that regulate how we metabolize nutrients have a 24-hour rhythm,” says Shives. “So they don’t work optimally if you eat in the middle of the night.”

The third to decline is your cognitive function. Driving is never a good idea when you are low on sleep, so try asking someone who has had a good night’s sleep to pick you up from the mall.

Your decision-making ability and impulse control will also decrease, says Shives, which plays well in the hands of retailers. You’re more likely to make unnecessary big purchases when your brain is half asleep.

Finally, getting back on track is going to be a bit difficult for at-will buyers.

“You’ll probably come home from shopping and sleep most of the day. Then they’re going to have a hard time sleeping that night. If they have to get up and go to work [Monday], they will have a very bad day.

Here are some tips to help you recover from your shopping expedition faster:

Avoid taking your children with you. Children have a harder time readjusting to a sleep schedule, says Shives. Leaving them at home will keep them on track.

Take a 20-minute nap. When you come home on Friday, don’t fall asleep for hours. Studies show that a 20-minute nap will leave you cooler than a longer nap.

Go to bed at a normal time. After your nap, stay up for as long as possible on Fridays, suggests Shives. If you fall asleep too early, you might wake up at 2 or 3 a.m., anxious to get back to the mall.

Wake up at a normal time. We know it’s the holidays, but don’t sleep too late on Saturday or Sunday morning. Otherwise, you will be quite shocked next Monday.

Happy shopping on Black Friday!