You should be getting 7—9 hours of sleep every night, blah blah blah, yeah, we know. But for a lot of people, that much sleep just isn't on the cards, at least right now. If you need to function on less sleep, here's what you should do to adjust to your new routine.

First of all, know there is no way to train your body to need less sleep.

Dr. Sigrid Veasey, a professor at the Center for Sleep and Circadian Neurobiology at the University of Pennsylvania’s Perelman School of Medicine told The New York Times that anyone who says they've taught themselves to need less sleep is just deluding themselves. Seriously, deluding themselves.

“The more you deprive yourself of sleep over long periods of time, the less accurate you are at judging your own sleep perception,” she said.

But it doesn't change the fact there are times in our lives where we just plain have to get by on less sleep.

On behalf of all the new parents, the people with new jobs that start earlier, and everyone else trying to adjust to getting less sleep, Business Insider consulted with psychologist and sleep specialist Michael Breus on the best ways to adjust to a (hopefully temporary) new routine.

1. Turn on/off the lights.

Anyone who's ever taken a photo in a florescent light lit room knows there are different types of light. Exposure to those different types of lights can directly affect your level of awake-ness

"The easiest way to keep somebody awake when they want to be asleep is with bright light," Breus tells Business Insider. He says he installed a bright Lighting Science light to help keep him awake.

Around bedtime, on the other hand, Breus says to limit your light exposure by using "blue blockers" like Swanwick glasses, that shield your eyes from the blue light (which stops melatonin production making it harder to sleep) emitted by computers, phones, and other gadgets.

There are also programs that block blue light on your devices, like F.lux, which can be installed on your computer and if you have a iPhone you can enable night shift (Settings >Display & Brightness > Night Shift) to change the color at a certain time each night.

2. Change what and when you eat.

You are what you eat. And as Breus puts it, "The gut is sort of your second brain."

If you're trying to get to bed earlier than your used to, eating an earlier dinner will help so your body has time to digest. But if you're looking to get more energy during the day, Breus suggests eating small meals heavy in protein and good fats—like avocado, olive oil, and nuts—throughout your day.

3. Get an energy boost from exercise.

You knew exercise would be on this list didn't you? Sigh.

Many find they get the biggest jolt by exercising first thing in the morning. While other opt for an afternoon pick-me-up. Breus says exercise can give you energy whenever you need it most.

4. The correct way to nap

Breus recommends the coffee nap, but with a caveat. He says it's okay to use the method for the first week or so while you're getting used to your routine, but using it on a regular basis is not healthy—because when the caffeine wears off, you're likely to crash.

To take a coffee nap, Breus says to pour yourself a cup of black drip coffee (because it has the highest caffeine content), throw some ice cubes in it and drink it quickly. Then lay down and take a 25-minute nap. When you wake up, the caffeine will have taken effect and you'll be extra awake.

Enough to get you through to your next proper sleep, anyway.