Why do we wake up? - psychological causes

The reason we wake up in the middle of the night is entirely situational. However, there are a few contributing elements that may cause this to happen on a more frequent basis.

Some psychological factors that cause us to wake up in the middle of the night include:

• Effects from medications such as beta-blockers, antidepressants, ADHD medications and NSAIDs. These can impact sleep and wake-up cycles.

• Stress can lighten your sleep and prevent you from attaining a deep, or REM, slumber.

• Anxiety disorders such as post-traumatic stress disorder (PTSD), bipolar disorder, depression and schizophrenia can induce sleep disturbances. In extreme cases, they can cause insomnia.

• Night terrors that cause screaming, thrashing or fear. They are more frequent during the NREM stage 3 of sleep and in children, although they can occur in adults as well. 

Why do we wake up? - other sleep issues

There are other sleep issues that can also impair your ability to get a full night's sleep, which include:

• Breathing difficulties caused by asthma, bronchitis or another lung illness.

• Sleep apnea can block your airways and make you stop breathing several times during the night. Your brain will wake you up and allow you to breathe again.

• Restless leg syndrome generates a tingling or prickling sensation in your legs, making you want to stretch or move them. It can be especially unpleasant at night.

• Digestive issues, particularly pain and coughing caused by acid reflux or symptoms of irritable bowel syndrome.

• It can occur during menopause, or in general, if you have hormonal imbalances. Sleep is sometimes disrupted by hot flashes and nocturnal sweats.

• Nighttime allergies can cause you to wake up in the night, such as dust mites, pollen, mould and pets.

• Going to the bathroom frequently. This could be due to high fluid intake or a medical condition.

Your wake up routine can alter how easy it is for you to wake up during sleep. If you follow your chronotype, it is more likely that you will sleep through the night. This is the inherent predisposition of your body to feel sleepy at a specific hour, or what most people refer to as being a morning lark or a night owl.

You can find out which category of sleep you fall into by taking our chronotype quiz.

How does your body wake up?

The brain area that plays a crucial role in waking up is the reticular activating system (or RAS). This brain area functions as a gatekeeper or filter, ensuring that it doesn't have to cope with any more information than it can manage. The brain is able to detect critical information to keep you alert during the day. This triggers the production of neurochemicals that cause other areas of the brain to wake up.

Researcher theories

Some research suggests that the concentration of particular chemicals in the cephalorachidian fluid drives the transition from sleep to wakefulness. This fluid surrounds the cells of the central nervous system to make us wake up.

However, the most widely used theory of awakening is that it occurs thanks to a series of neurotransmitters. Examples of these are acetylcholine, orexin, histamine, serotonin, norepinephrine and dopamine. These awaken a group of neurons responsible for memory, reasoning and learning, thus initiating consciousness.