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Table of Contents
- Do you really wake at 3am every night?
- Sleep architecture: why waking is more likely after the first few hours
- Why we wake at all: the brain's safety checks
- What wakes you up is not what keeps you awake
- Why older adults wake more often
- Stress, cortisol and the 3am myth
- Cortisol, a fixed wake time and sleep inertia
- When to seek help
- Waking at 3am FAQs
Do you really wake at 3am every night?
Why do you wake up at 3am? Well, despite what social media says, you almost certainly don't. Night-to-night sleep is quite variable, and so is when you wake up; for instance, this week I woke up at 01:11, the next night at 02:48, then the next night at 04:15, and lastly, I slept through the night. Several factors can influence the time you wake in the night, including what time you went to sleep and how little sleep you had the night before.
Sleep architecture: why waking is more likely after the first few hours
Waking up at 3am depends on what we call sleep architecture. Let me explain: when we fall asleep at the start of the night, we enter our deepest sleep, called N3 sleep, within about 20 minutes. N3 sleep makes up about 25% of the night in adults, but it occurs predominantly in the first third of the night. It's called deep sleep because it's very difficult to wake up from it, which can mean we can sleep through a partner's snoring, a thunderstorm or things like that. Because of this, it's not likely that we wake up naturally in the first third of the night.
Now you may have heard about sleep cycles, where during the night we repeatedly cycle through the 4 stages of sleep: N1-N2-N3-REM. It is often stated that each cycle lasts 90 minutes, but in fact they vary a great deal, lasting about 70-120 minutes. While it is difficult to wake during N3 sleep, we are preferentially designed to wake during Rapid Eye Movement (REM) sleep, which makes up about 20-25% of the night. While there may be a small amount of REM at the end of the first sleep cycle, it is not until the end of the 2nd cycle that you are likely to wake up.
So, if you have two sleep cycles in that first part of the night, it will be around 3-4 hours before you wake; thus, depending on when you fell asleep, this means that you will wake sometime around 3am. This isn't to say we can't wake in the other stages of sleep. However, wakings are far more prevalent in the second two-thirds of the night than in the first third, and the long REM period at the end of the second sleep cycle provides the first likely opportunity for an awakening.
Why we wake at all: the brain's safety checks
However, as I said, sometimes you may sleep through the night, so what causes us to wake up? Well, it may surprise you to know that we wake up numerous times during the night; however, these wakings last only a second or so, so we don't remember them. These short awakenings check that we are safe and sound and that it is OK to keep sleeping. Being asleep makes us very vulnerable; from an evolutionary point of view, being unconscious for 8 hours would make us an easy target for the next village to attack us or for some large animal to eat us. This means that we can only sleep if we feel safe and secure, and these short awakenings reassure the brain that the world is free of threats. This is also why parents can hear the tiniest sound from their infants.
However, if a 'signal' is strong enough, it will wake you up. This 'signal' can be internal or external. Examples of internal signals are pain, choking or needing to go to the bathroom. External signals can include your partner moving or snoring, lorries going past or being too hot or too cold. If these signals are strong enough, they will wake you up.
What wakes you up is not what keeps you awake
A key thing to understand is that what wakes you up is not necessarily what keeps you awake. You can wake up for whatever reason and then go straight back to sleep. Most likely, you wouldn't actually see that as a problem. However, we commonly wake up and find our minds racing; we start tossing and turning, and we can't fall back asleep. To deal with middle-of-the-night waking, it's important to address both what wakes us up and what keeps us awake. They can be two very different things; for instance, you wake up needing to pee, you go to the bathroom, but then find yourself unable to fall back asleep for an hour or so because of pain, your partner snoring, or your mind racing. Additionally, you get frustrated about not falling back asleep.
So, we need to see whether we can stop ourselves from waking up. Can we address whatever keeps us awake, or do something about what's keeping us from falling back asleep?
For instance, if you frequently wake up needing the bathroom, try reducing how much liquid you consume before bed. Alcohol, while it may help you fall asleep, disturbs your sleep in the later part of the night. If your partner's snoring wakes you, either invest in earplugs or explore remedies that could reduce the snoring. Many illnesses can disturb sleep, so it is important to treat them effectively; however, be aware that many commonly used medications can also disturb sleep (if you feel your illness or medications are disturbing your sleep, see your healthcare provider).
Why older adults wake more often
Older adults have more awakenings because, as we age, we progressively lose deep, N3 sleep, so we have more opportunities to be woken. Sleep becomes lighter and more easily disturbed, and as they get older, there are more things, such as pain, anxiety, illness, etc., that may wake them up.
Stress, cortisol and the 3am myth
You may have seen on social media about stress and cortisol regarding this waking at 3am. However, stress won't wake you up on its own. If you are stressed or your nervous system is more active, that can show up as difficulty falling asleep at the start of the night. But when you wake up in the night, it can be for a myriad of other reasons. However, once you are awake, your mind can start racing if you are stressed about something, and cortisol can rise in response, making it hard for you to switch off and fall asleep. Stress activates your 'fight or flight' response; you become hyper-aware of your environment, looking for threats to fight or run from. Neither state is conducive to sleep.
Now, if you find yourself tossing and turning with your mind racing, the advice is that if you've been awake in the night for about 20 minutes or so, it's wise to get out of bed, go somewhere quiet, do something relaxing and only go to bed when you feel sleepy again, because if you're not sleepy, then there's little point trying to sleep. So, stress can hamper sleep, but so can stressing about your sleep; getting more frustrated about your lack of sleep, or worrying you'll feel terrible the next day won't help you fall asleep.
Cortisol, a fixed wake time and sleep inertia
Cortisol levels fall over the night, and unless you wake up in the night and start stressing about something, they only start increasing about 90 minutes before you wake up, along with an increase in body temperature. This increase is part of the waking process, ensuring your body and brain are ready for your intended wake time. This is one of the reasons why sleep experts put such a strong emphasis on having a fixed wake-up time, because if your body and brain know when you're going to wake up, then it can prepare to get you bright-eyed and bushy-tailed at that time. If your wake time is too variable, you may experience 'sleep inertia', i.e., that groggy feeling upon waking, which can last up to two hours for some people.
When to seek help
Waking in the middle of the night and being unable to fall back asleep can be very frustrating. Some things that wake us or keep us awake can be easily addressed; others may require help from a healthcare provider. However, most supplements and products claimed to help with middle-of-the-night awakening have little, if any, scientific evidence supporting their effectiveness. The recommended therapy is Cognitive behavioural therapy for insomnia, which may be helpful.
Waking in the night is normal. What matters is not the time on the clock, but whether you can let yourself go back to sleep once you are awake.
Waking at 3am FAQs
Why do I wake up at 3am every night?
Most people do not wake at the same time each night, even if it feels that way. Deep N3 sleep dominates the first third of the night and is hard to wake from, while the long REM period at the end of the second sleep cycle offers the first likely chance of waking, roughly three to four hours after falling asleep. Depending on when you went to sleep, that window often falls somewhere around 3am. Night-to-night variation in bedtime, sleep debt and disturbances means the exact time moves around considerably.
Does cortisol wake you up at 3am?
Not on its own. Cortisol falls through the night and only begins to rise around 90 minutes before your usual wake time, as part of the normal process of preparing the body to get up. Stress is more likely to make it hard to fall asleep at the start of the night than to wake you in the middle of it. Once you are awake, however, a racing mind can trigger a stress response and a rise in cortisol, which makes it harder to drop back off.
Is it normal to wake up during the night?
Yes. Adults wake many times each night, usually for only a second or so, and these brief arousals are not remembered in the morning. They appear to serve a protective function, allowing the brain to check that the environment is safe before sleep continues. A full awakening only happens when a signal, such as pain, needing the toilet, a snoring partner or a room that is too hot or cold, is strong enough to override this.
Why can I not get back to sleep after waking in the night?
What wakes you and what keeps you awake are often two different things. You may wake to use the toilet and return to bed easily, only to lie awake because of discomfort, noise or a mind that has started racing. Frustration about being awake then adds to the problem. Addressing both causes separately, the trigger for waking and the reason for staying awake, is the most effective approach.
Should I get up if I wake in the night and cannot sleep?
If you have been awake for around 20 minutes and are becoming restless, the standard advice is to get out of bed, go somewhere quiet and do something relaxing until you feel sleepy again. Lying in bed trying to force sleep when you are not sleepy tends to prolong wakefulness. Returning to bed only when sleepy helps keep the bed associated with sleep rather than struggle.
Why do older adults wake more often at night?
Deep N3 sleep declines progressively with age, so sleep becomes lighter and more easily disturbed, giving more opportunities for a full awakening. Older adults are also more likely to experience pain, illness, anxiety or the effects of medication, any of which can disturb sleep. If night waking is affecting daytime functioning, it is worth discussing with a GP, since both underlying conditions and some common medications can be a factor.
