An NHS doctor has explained why people often wake up at 3am, linking it to cortisol levels, blood sugar dips and hormonal changes, particularly in women going through perimenopause and menopause.
Dr Amir Khan, who regularly appears on Lorraine and This Morning, said the early-morning awakenings are down to the body's natural stress hormone and can lead to a racing heart and full wakefulness.
The 3.29am average and circadian rhythm
Some research has shown the exact average time people wake up is 3.29am, linked to the body's circadian rhythm. John Hopkins Medicine said most adults naturally wake up two to three times per night, many as brief "micro-arousals" lasting only a few seconds that are not remembered.
Dr Dan Gartenberg of Sleepspace said the human circadian rhythm reaches its lowest body temperature and highest fatigue point typically around 3am, making partial or full awakenings around this hour very common.
What happens in the body at 3am
Dr Khan said on Instagram: "Have you ever noticed that you fall asleep just fine and then suddenly you’re awake at 3:00 a.m. staring at the ceiling, overthinking your entire life? Well, there’s actually a biological reason for that. Around 2 to 4 am, your body is in a very particular phase of its sleep cycle."
He explained that hormones are responsible: "Cortisol, your natural stress hormone, starts to rise in preparation for waking up. It’s completely normal. But if you’re already stressed, anxious, or running on empty, that small hormonal shift can be enough to tip you into wakefulness. At the same time, your brain is more vulnerable. During the night, especially in the early hours, blood sugar levels can dip slightly."
"If they drop too low, which is more likely if you’ve had alcohol, eaten very late, or are under chronic stress, your body releases adrenaline to compensate. That little surge can wake you up suddenly with a racing heart or a sense of alertness. Add in the fact that at 3am there are no distractions, no emails, no noise. Just you and your thoughts and your brain’s threat system becomes louder."
Hormones and the worry cycle
Dr Khan said it may be worse for people who regularly get disturbed sleep. He explained: "The amygdala, the part of the brain that processes fear, is more reactive when we’re sleep-deprived. So worries that feel manageable at 3pm can feel catastrophic at 3am. Hormones also play a role in perimenopause and menopause."
"Fluctuating oestrogen affects temperature regulation, cortisol sensitivity, and sleep stability. That’s why so many women report early morning awakenings and poor sleep itself becomes part of the cycle. The more you worry about waking up, the more likely you are to wake up."
He reassured that waking briefly in the night is normal: "Now, waking briefly in the night is actually normal. We all cycle through lighter sleep every 90 minutes. The problem isn’t waking up, it’s the anxiety about being awake. So, gentle breathing, avoiding clock watching and screens, and keeping evenings calm and alcohol light can really help. So, if you’re awake at 3:00 a.m., it doesn’t mean you’re broken. It just means your biology is doing what biology does and we just need to help it along a little bit."
One follower responded: "Thank you so much for this Amir. This is so me, I wake up between 2am and 3am most nights, it’s like an alarm goes off and I’m wide awake feeling terrified, of what I don’t know, but it’s awful. Thank you so much for explaining so brilliantly."
Another asked about dietary help for blood sugar-related waking, noting they are perimenopausal and wake at 2:58am like an alarm.
