If you are having trouble falling asleep, you are in good company. About 65% of Americans said they have sleeping problems a few nights each week, according to a recent study by the National Sleep Foundation. Sleeping too little can lead to a higher risk of becoming fat and getting depressed . But before you go to a doctor for advice, it is worth examining your sleeping habits one more time. Some of your favorite evening habits may have something to do with the sleeping problems. Setting a Bright Alarm Clock The light of your bright alarm clock can prevent you from falling asleep. You can make your room as dark as possible. Cover the bright numbers with a book or consider buying a small travel clock. Your cellphone alarm may also do the trick. Counting Sheep When you just can't  fall asleep, it's useless to stay in bed to count sheep. If you've been trying to fall asleep for more than 30 minutes, the National Sleep Foundation suggests you get up to do some reading or watch TV for a while. Such activities will make you sleepy. Before you know it, you'll be going back to bed really tired. Exercising Late at Night? Daytime workouts  will keep you full of energy for hours. That's why you don't want to exercise within three hours of _ . Fierce   physical activity raise your body temperature and pumps your energy level--both are bad for a good night's sleep. By writing the passage, the writer mainly wants to tell us   _  .
why so many people can't sleep well at night how to enjoy a good night's sleep that sleeping problems are troubling more and more people that people may solve their sleeping problems by some habits
Question: If you are having trouble falling asleep, you are in good company. About 65% of Americans said they have sleeping problems a few nights each week, according to a recent study by the National Sleep Foundation. Sleeping too little can lead to a higher risk of becoming fat and getting depressed . But before you go to a doctor for advice, it is worth examining your sleeping habits one more time. Some of your favorite evening habits may have something to do with the sleeping problems. Setting a Bright Alarm Clock The light of your bright alarm clock can prevent you from falling asleep. You can make your room as dark as possible. Cover the bright numbers with a book or consider buying a small travel clock. Your cellphone alarm may also do the trick. Counting Sheep When you just can't  fall asleep, it's useless to stay in bed to count sheep. If you've been trying to fall asleep for more than 30 minutes, the National Sleep Foundation suggests you get up to do some reading or watch TV for a while. Such activities will make you sleepy. Before you know it, you'll be going back to bed really tired. Exercising Late at Night? Daytime workouts  will keep you full of energy for hours. That's why you don't want to exercise within three hours of _ . Fierce   physical activity raise your body temperature and pumps your energy level--both are bad for a good night's sleep. By writing the passage, the writer mainly wants to tell us   _  .
A. why so many people can't sleep well at night
B. how to enjoy a good night's sleep
C. that sleeping problems are troubling more and more people
D. that people may solve their sleeping problems by some habits
Answer: