1. Sleep Cycles Are Not Fixed at 90 Minutes
After you fall asleep, you move between non-REM and REM sleep several times. The length of each cycle and the proportion of each stage vary from person to person, and can even change throughout the night for the same person. That is why simply calculating sleep as a multiple of 90 minutes cannot guarantee how refreshed you will feel when you wake up. Use a sleep calculator as a reference tool for planning your bedtime.
2. Make Sure You Get Enough Sleep First
The National Heart, Lung, and Blood Institute generally recommends 7–9 hours of sleep per day for adults and 8–10 hours for teenagers aged 13–18. The amount you need varies from person to person. Tracking your sleep duration without an alarm, daytime sleepiness, and ability to concentrate for several days can help you determine whether you are getting enough sleep.
3. Keep a Consistent Wake-Up Time
Keep your wake-up time as consistent as possible on weekdays and weekends. Then, count backward from that time using the amount of sleep you need and the time it takes you to fall asleep, and begin your bedtime routine accordingly. If naps interfere with your nighttime sleep, avoid napping late in the afternoon. Sleep-stage estimates from wearable devices and apps are not the same as medical tests, so it is best to treat them only as rough lifestyle records.
4. Create an Environment That Makes It Easier to Sleep
Keep your bedroom quiet, dark, comfortable, and cool. During the hour before bed, reduce exposure to bright screens and strenuous activity, and try creating a short routine you follow in a similar order each night, such as washing up and reading a book. Caffeine, nicotine, and alcohol can interfere with sleep. Although alcohol may make you feel sleepy at first, it can increase awakenings during the night.
5. Do Not Underestimate Sleep Deprivation
A lack of sleep can reduce your attention and judgment the next day, increasing the risk of accidents while driving or working. When this continues for a long time, it is also associated with health problems such as obesity, high blood pressure, diabetes, and heart disease. Do not drive when you are drowsy. If you remain severely sleepy despite getting enough sleep, or if loud snoring and repeated pauses in breathing occur, seek medical care.
6. When Insomnia Persists
If difficulty falling asleep or frequent awakenings continue and begin to affect your daytime life, keep a sleep diary and share it with a healthcare professional. Cognitive behavioral therapy for insomnia (CBT-I) is commonly used as the first-line treatment for chronic insomnia. Sleep restriction therapy does not mean arbitrarily cutting down your sleep time, so do not try it without professional guidance. Sleeping pills and melatonin can also interact with other medications, so consult a healthcare professional before taking them.