If some people feel still sleepy despite ostensibly getting enough hours of shuteye, it could be because they are not sleeping deeply enough, according to Prof. Yun Chang-ho at Seoul National University's Bundang Hospital.
Deep sleep generates delta brainwaves, and growth hormone discharged during sound sleep renews damaged cells and relieves both physical and psychological stress. Energy is stored in cells during deep sleep, helping you get through the day.
Here are five tips for making sure you sleep deeply enough.
◆ Avoid Watching TV or Using Your Phone Just Before Going to Bed
Some people say they fall asleep more easily if they watch TV or look at their phone as they are about to sleep, but it is a bad habit that obstructs deep sleep. The light emanating from the screen stimulates the brain and gives out a signal that it is daytime. By delaying the circadian rhythm, light keeps the brain alert even if you keep your eyes closed.
☞ Turn off all the lights as well as the TV and smartphone before going to sleep.
◆ Break the Habit of Snoozing
Sleeping beyond the set time may be bad for you. Spending five more minutes in bed may sound sweet, but those five minutes do not help the quality of sleep at all. On the contrary, they may make falling asleep at night more difficult by delaying the time the brain wakes up. If you can afford to sleep for five or 10 more minutes in the morning, set the alarm clock five to 10 minutes later in the first place.
☞ Wake up at the first alarm.
◆ Avoid Eating Before Going to Bed
Some people say they fall asleep more easily when their stomach is full. The digestive system usually goes into sleep mode as well at night, but eating in the middle of the night wakes up your stomach, and this disrupts deep sleep.
☞ Do not eat for at least two hours before you go to bed. If hunger is irresistible, have just a few carbohydrates that are easy to digest.
◆ Be Active
If you move around a lot during the day, your desire for a good night's sleep increases. If you increase your body temperature a little by doing light exercise before going to bed, your body temperature will start to drop when you lie down and make you fall asleep more easily. However, excessive exercise before going to bed will have the opposite effect as it wakes up the brain.
☞ Do light exercises for about half an hour two hours before going to bed.
◆ Avoid a Siesta
Taking frequent naps every time you feel sleepy will not help you get a good night's sleep. If you sleep during the day when the brain is supposed to be alert, you will have trouble falling asleep at night. If you are too sleepy to concentrate, take a cat nap.
☞ If you must, take only a brief cat nap for about 20 to 30 minutes.