He should go to urology to be investigated. There are many possible reasons:
1) Peeing too slowly, so you stop peeing before emptying bladder. This means bladder starts off partly full, so it fills up faster. (Everyone pees slower at night anyway, increasing the risk of peeing to slowly at that time if your flow rate wasn't good to start with.)
2) Bladder spasms, where the bladder contracts generating an urge to go, before the bladder had filled up.
3) Drinking too much fluid too near bed time, possibly combined with your body's night time antidiuretic hormone mechanism (to prevent kidneys generating much urine overnight) not working as well as it did when you were younger.
4) Taking diuretic medications too late in the day.
5) Oedema in lower body/legs, which is more likely to drain back at night when you are laying down.
I would suggest you keep a peeing diary, recording the time, urgency (how badly you needed to go), and volume each time you pee. You can also add to it time and volume of fluid intake. This may be useful data to take with you to see the urologist.
1) and 2) can often be helped by drugs.
3) Avoid drinking fluids 2-3 hours before bedtime.
4) Check medication instructions, and if you take a diuretic any time other than first thing in the morning, check with your GP if the instructions are correct.
5) Oedema - keep your feet elevated when sitting down. Ask your GP if you can have some diuretic medications to reduce oedemia. It can be caused by some common drugs too, such as amlodipine, but don't stop taking it - you need to go through alternatives with your GP.