Why do I wake up at 3am?
Quick answer
Regularly waking around 3am is most often caused by a drop in blood sugar that triggers a rise in cortisol and adrenaline, by alcohol wearing off, by hormonal changes such as perimenopause, or by a stressed nervous system. Low magnesium and a warm bedroom make it worse. Inflammation, medication effects and other health conditions can also play a role.
Waking at the same time every night, wide awake and thinking, is a pattern, not bad luck.
The blood sugar and cortisol link
When blood sugar falls in the early hours, your body releases cortisol and adrenaline to raise it. That alarm signal wakes you up. A dinner low in protein, high in fast carbohydrates, or eaten very early can set this up.
Alcohol and late eating
Alcohol helps you fall asleep but is metabolised within a few hours, leaving a rebound of alertness in the second half of the night. Heavy late meals keep digestion and body temperature up.
Hormones and life stage
Falling progesterone and fluctuating oestrogen in perimenopause commonly cause early waking and night sweats. In men and women, long-term stress shifts the cortisol rhythm so it rises too early.
What to check first
- Fasting glucose, HbA1c or a two-week glucose sensor
- Morning cortisol pattern if stress is high
- Magnesium status and the calcium to magnesium ratio
- Female hormones if over 40 with cycle changes
- Overnight heart rate and HRV from a wearable
What can affect the result
A late or very early dinner, alcohol, a stressful day, room temperature, a new medication and the time of your cycle all shift sleep from one night to the next. One bad week says less than a pattern over a month.
What your own history can tell us
Previous symptoms, major life changes, medication, hormone changes, illnesses, travel, sleep patterns, old bloodwork and earlier test results can all change how a result is understood. Over time, repeat testing gives us something even more useful: your own trend.
When to see a doctor
See a doctor if waking comes with heavy snoring or gasping, chest pain, palpitations, night sweats without a clear reason, or ongoing low mood or anxiety.
How Reset looks at this
We do not read one result in isolation. We read it alongside your history, symptoms, lifestyle, environment and any other data you already have. The aim is not to give you more information. It is to work out what deserves attention first.