Wakeing up with headaches,any thoughts?

I wake up with a headache if I haven't slept well or enough.

Too much reading or TV? Bedroom too warm. Poor light. Dehydration. Tiredness. All those reasons give me a headache.

I do too, but it is mild, always suffered migraine and on meds for same. Mine always clears quickly but is always worse if I fail to keep window open a crack.
Sorry not to offer solution or advise on anything more.

Lots of very credible suggestions here- my immediate reaction was dehydration or possibly blocked sinuses (or a sinus infection) or your pillow and sleeping position.
Some swear by sleeping with the bedroom windows open, others, closed, but as long as the room is well aired during the day it should be a matter of choice.
Are these headaches the lingering “gnawing” sort or sharp and severe? Do they pass after your first TIB?
If you have tried all the things suggested and the headaches continue, especially if they get worse, it is always wise to seek medical advice, even if only to put your mind at rest.

I had a similar problem with the addition of a mild sore throat every winter. I bought a carbon monoxide monitor, no problem there. It turned out to be the ever increasing number of woodburning stoves in the area. Every winter now I seal my bedroom window with tape and run an air purifier overnight and have not had the problem since.

Blocked sinuses?

Do you have a carbon monoxide alarm. If not, buy one.
Cheap as chips.

Too much beer in Wetherspoons 🤷🏻‍♀️?

I suggest that it is either dehydration, which is easily remedied or your sleeping position, so perhaps have a look at your pillows…….are they right for you? Do they need replacing?

How severe are your headaches? Do they clear once you are up
and about? Are you nauseous?

Teeth grinding?

I would suggest dehydration as another poster has done, especially if your heating is on at night producing a warm dry environment and if you mouth breathe when asleep. Take a full glass of water to bed and whenever you wake for the loo etc have a drink.

Is your bedroom too warm during the night? I hope you soon find some relief.

Migraine?

Could be dehydration. Do you feel better after you've had a drink?

I've recently seen advertisements for spectacles that claim to reduce the strain of glare from screens - not sunglasses, but look like standard specs.

Windows not being open? Well if you must, especially if you fancy a spot of pneumonia.

Don't.

Otherwise, all that springs to mind is Co-codamol, the strongest painkiller legally available over-the-counter.

After that, it looks like a job for the GP.