Snack on cheese and crackers

The ideal nighttime nosh combines carbohydrates and either calcium or a protein that contains the amino acid tryptophan—studies show that both of these combos boost serotonin, a naturally occurring brain chemical that helps you feel calm. Enjoy your snack about an hour before bedtime so that the amino acids have time to reach your brain.

Some good choices:

1 piece of whole grain toast with a slice of low-fat cheese or turkey
Banana with 1 teaspoon of peanut butter
Whole grain cereal and fat-free milk
Fruit and low-fat yogurt

Sip milk, not a martini

A few hours after drinking, alcohol levels in your blood start to drop, which signals your body to wake up. It takes an average person about an hour to metabolize one drink, so if you have two glasses of wine with dinner, finish your last sip at least 2 hours before bed.

Take time to wind down

"Sleep is not an on-off switch," says Dr. Breus. "It's more like slowly easing your foot off the gas." Give your body time to transition from your active day to bedtime drowsiness by setting a timer for an hour before bed and divvying up the time as follows:

First 20 minutes: Prep for tomorrow (pack your bag, set out your clothes).

Next 20: Take care of personal hygiene (brush your teeth, moisturize your face).

Last 20: Relax in bed, reading with a small, low-wattage book light or practicing deep breathing.

Write down your woes

"The number one sleep complaint I hear? 'I can't turn off my mind,' " says Dr. Breus. To quiet that wakeful worrying, every night jot down your top concerns—say, I have to call my insurer to dispute that denied claim, which will take forever, and how can I spend all that time on the phone when work is so busy? Then write down the steps you can take to solve the problem—I'm going to look up the numbers before breakfast, refuse to stay on hold for more than three minutes, and send e-mails tomorrow night if I can't get through—or even I can't do anything about this tonight, so I'll worry about it tomorrow. Once your concerns are converted into some kind of action plan, you'll rest easier.

Cut caffeine after 2 pm.

That means coffee, tea, and cola. Caffeine is a stimulant that stays in your system for about 8 hours, so if you have a cappuccino after dinner, come bedtime, it'll either prevent your brain from entering deep sleep or stop you from falling asleep altogether.

Exercise, but not within 4 hours of bedtime

Working out—especially cardio—improves the length and quality of your sleep, says Dr. Shives. That said, 30 minutes of vigorous aerobic exercise keeps your body temperature elevated for about 4 hours, inhibiting sleep. When your body begins to cool down, however, it signals your brain to release sleep-inducing melatonin, so then you'll get drowsy.

Review your medications.

Beta-blockers (prescribed for high blood pressure) may cause insomnia; so can SSRIs (a class of antidepressants that includes Prozac and Zoloft). And that's just the beginning. Write down every drug and supplement you take, and have your doctor evaluate how they may be affecting your sleep.