Waking Up Wide Awake Between 2 AM and 4 AM... Why You Shouldn't Sleep Immediately After Working Late

[Anchor]

Have you ever found yourself inexplicably waking up between 2 AM and 4 AM? Once you are awake, it is naturally difficult to fall back into a deep sleep. We take a look at why people frequently wake up in the middle of the night and how to achieve a sound, restful sleep.

[Reporter]

The autonomic nervous system or stress-related hormones are definitely involved in this phenomenon.

The autonomic nervous system acts to detect threats and alert the brain.

If we think back to primitive times, a lion could threaten us at any moment while we were sleeping. In such dangerous situations, even the slightest rustle would cause us to wake up.

There is a clear reason for waking up: an increase in stress hormones, or an imbalance in the autonomic nervous system where the sympathetic nervous system becomes overly active and the parasympathetic nervous system drops, causing brain hyperarousal.

Cause ① Stress

Many people, myself included, experience a lot of trouble falling asleep, waking up too early in the morning and struggling to fall back asleep, or waking up far too quickly whenever they are in pain, stressed, or harboring worries.

There is a stress hormone called cortisol, which should ideally be secreted during the day and suppressed at night to help you sleep.

If you are under a lot of stress and feeling tense, stress hormones continue to be secreted even while you sleep.

Because the rise in stress hormones and the activation of the sympathetic nervous system happen together, there are quite a few people who actually wake up sweating or experiencing heart palpitations in the middle of the night. Simply put, they end up worrying about their concerns even in their dreams.

Cause ② Sleep Apnea

Among the patients actually treated in hospitals, the number one cause is sleep apnea.

It is common among middle-aged adults after their 40s, especially men, and particularly in those with thick necks or sudden weight gain, whose airways tend to narrow repeatedly during sleep.

Since breathing is blocked during sleep, the brain naturally wakes up so that tension can be applied to the airway, preventing deep sleep.

Cause ③ Delayed Sleep Phase Syndrome

One of the common causes among young people is what is known as "delayed sleep phase syndrome."

Normally, sleep hormones are secreted around 12 AM to help induce sleep, with waking expected at 6 AM to 7 AM, but instead, secretion is delayed until around 3 AM to 4 AM and continues until 10 AM to 11 AM, shifting the schedule backward.

When this schedule is delayed, fatigue accumulates during the day when you need to go to work, leading to falling into a light sleep at night and waking up early in the morning. However, if this bounces back and forth irregularly due to lifestyle habits of sleeping and waking late or early, sleep hormones are not secreted on a consistent schedule.

If you have worked a late shift, going straight to bed is generally not recommended. Why? Because when you work, you become stimulated. As mentioned earlier, the autonomic and sympathetic nervous systems are activated, and stress hormones like cortisol are elevated. You need to let your stimulated nervous system settle down for at least an hour or two after getting off work before going to sleep in order to achieve deep sleep. However, because you are tired from working late, you rush into sleep just to satisfy the immediate need for rest, which causes you to wake up as soon as that urgent need is met.

Sleep deprivation is considered unconditionally bad. You can think of it as increasing the risk of all kinds of diseases. There is something called the glymphatic system. It is a brain-cleansing process that takes place while you sleep, and it occurs more during the latter half of sleep rather than the first half.

You can think of the early part of sleep as a time for the brain and body to rest, while the latter part is a time for the brain to wake up again, actively clean itself, and regenerate. If you wake up frequently at dawn and your total sleep time decreases, the latter half of your sleep becomes more deficient, which accelerates brain aging.

The most important thing is consistency. Professionally, that can be difficult to maintain, but schedules must be planned with this in mind.

Because people are short on sleep during weekdays, they commonly tend to sleep in until 11 AM or 12 PM. Going to sleep late at 2 AM, 3 AM, or 4 AM on the weekend and shifting your schedule is the worst thing you can do; it is called social jetlag—the time difference between weekends and weekdays. Textbook guidelines suggest keeping it within one to two hours.

The second most important factor is light. The melatonin cycle is most heavily influenced by light.

What should you do before bed? Keep it dark. Simply refraining from bringing your smartphone into bed can greatly improve your sleep.

Additionally, exercising is certainly helpful. I exercise a lot, walking 10,000 steps a day. In fact, what I recommend is strength training. Substances released during muscle workouts are known to have a very positive impact on our sleep.

How can you tell if you should be thinking, "Am I in a serious state? Should I go see a doctor?"

The first criterion is whether your sleep issues interfere too much with your work during the day, causing functional impairment. The second criterion is anticipatory anxiety—feeling anxious even before going to bed out of the worry that you might wake up in the middle of the night again. That is a somewhat negative sign. If that is the case, you should think, "Do I need to manage this?" And if this repeats for two or three days or more a week, you should consider seeking help.
※ Please note: This article was translated by AI and may contain errors.