You fall asleep fine. Then at roughly 3am you are wide awake, heart going slightly faster than it should be, brain helpfully producing a list of everything you have ever done wrong.
It is easy to file this under anxiety. Frequently it is glucose.
What happens overnight
Blood glucose drifts down across the night, which is entirely normal. If it drops far enough, your body treats it as a problem worth solving and releases cortisol and adrenaline to prompt the liver to release stored glucose.
Both of those are alerting hormones. You wake up.
The racing thoughts arrive after the adrenaline, not before it. Which is precisely why calming techniques help you get back to sleep but do nothing to stop it happening again the next night — you are treating the symptom at the wrong end of the chain.
Why this is more common with PCOS
Insulin resistance produces bigger glucose swings in both directions. A larger post-dinner rise means a steeper subsequent fall, and that fall is what lands in the small hours.
Add the raised cortisol many of us carry from an over-full day, and the threshold for waking gets lower. The mechanism is in the cortisol loop.
Waking at the same time nightly is a pattern. Patterns have mechanisms, and mechanisms have levers.
The dinner change
Protein and fat at the evening meal slow the overnight drop considerably. A carbohydrate-heavy dinner eaten early produces a rise, then a fall that lands squarely at 3am.
Three things that help, in order of effort:
Add protein and fat to dinner. Not more food overall — different proportions.
Sequence the meal. Vegetables and protein before the starch flattens the initial spike, which flattens the later dip. See meal sequencing.
If dinner is early, add a small protein-containing snack before bed. Yoghurt, a boiled egg, cheese and oatcakes. This is the single most effective fix if you eat at 5.30pm with children and go to bed at 11pm.
How to test whether this is your problem
Try the bedtime snack for a week and note what happens. It is a cheap, fast, low-risk experiment, and the answer is usually clear within a few nights.
If the waking persists regardless of what you eat, look elsewhere — particularly at the timing of your body clock via morning light.
When it is not glucose
Night sweats, snoring, morning headaches or a partner reporting pauses in your breathing all point toward sleep apnoea, which is meaningfully more common with PCOS and routinely missed in women. That deserves proper investigation rather than a snack — see the apnoea guide.
Persistent early waking alongside low mood, loss of interest or hopelessness is worth raising with your GP. That combination has its own explanations and its own treatments.
Questions people actually ask
Is a bedtime snack not bad for blood sugar?
A small protein-led snack does not produce the kind of spike that causes problems, and it prevents the dip that wakes you. A bowl of cereal at 10pm is a different proposition.
Why 3am specifically?
It tends to fall three to five hours after your glucose peaks, combined with the natural early-morning cortisol rise beginning. The exact time varies with when you ate.
Does alcohol make this worse?
Considerably. Alcohol helps you fall asleep and then disrupts the second half of the night, including through its effect on blood glucose. The 3am waking after wine is very well documented.
Should I check my glucose overnight?
A continuous glucose monitor can show you the dip directly and some people find that genuinely clarifying. It is not necessary — the snack experiment answers the same question for free.
More in the sleep section.