We’ve already started a list of the Dos and Don’ts of Dozing in previous lessons. You know to avoid your bedroom being too warm. You know to turn off gadgets that emit light and noise. And you have something of a checklist every night with your sleep-enhancing routine -- which by now should be becoming a habit.

But there is further research-based evidence about additional behaviors to avoid. The challenge this time is cut out as many of the following eight behaviors as you can (if you’re even doing them in the first place):

• Don't watch television or work in your bedroom. You want your brain to think of the room as only for sleep (and sex).
• Shut off the news and put down your smartphone. It’s not just that you want to avoid brain-stimulating blue light the hour or so before bed, you also want to avoid emotionally stimulating news or drama on Facebook.
• Sorry, smokers, nicotine is also a stimulant. Smokers are four times more likely to say they feel tired when they wake up than nonsmokers, according to one study. Consider it yet another reason to kick the habit.
• Regular exercise does help with sleep, but you may want to avoid it in the couple of hours before you head off to dreamland. While studies haven't proven that exercise just before bed will harm sleep, many experts -- like the World Sleep Society -- recommend avoiding it. Why? Because moderate exercise heats up your core temperature, signaling the body that it's time to be awake. And all those lovely feel-good endorphins that exercise provides is thought to keep some of us alert.
• OK, brace yourself, pet lovers. No furry friends in bed. Every little purr or tail wag is likely to disrupt your sleep, no matter how much you enjoy cuddling. Plus, the animal dander Fido and Fluffy bring with them into the bedroom can trigger reactions in people with allergies, further disrupting slumber.
• If you like to read to fall asleep, don’t do screens. Try books or long-form magazines. If you love your electronic reader device, look for models without backlights or the ability to turn that function off.
• Don’t just lie there if you’re all keyed up. Try deep breathing or other mindfulness exercises to unwind. Mantras help some people, as does prayer, or try list-making or visualizations and progressive muscle relaxation. Counting sheep is classic.
• Finally, if you just can’t sleep, don’t force it. After trying for, say, 20 minutes, get up, go do something relaxing until you get tired, and come back to bed then. Tossing and turning in bed is a recipe for anxiety, which will further inhibit your sleep.