Older story, but worth a look.

kayaker has unplanned overnight

A small kit (and a big plan) would have made all the difference

Note that the group started the trip at 2 PM, not much daylight left at this time of year.

"You will never regret starting too early, you will always regret starting too late." - Gaston Rebuffat

"found around 5:30 AM" That's good, but it would have been even better if she had been found around a fire - which of course would have rendered the finding much easier....

To be fair, the newspaper article is dated 28 June so there must have been at least 6 hours of daylight left.

At any rate, I'm pretty sure the problem could be avoided easily with a little organization and planning. On any outdoor trip, boating excursion, trek etc. always keep an eye out for your buddies - and make sure they do the same for you. If at all possible, check everyone's position periodically (even if you're not the designated group leader). Picking a rally point or two along the way can be very helpful, ideally a conspicuous landmark easily visible from afar.

Handheld radio transceivers can be a huge asset in that kind of situation. License-free (FRS/GMRS/PMR/CB) or ham radio, doesn't really matter as long as it works for you. Also, it's very important to have some good means of signalling for rescue. A whistle worn securely on one's person would be a bare minimum. Maybe a flare, too. It's a great way to attract attention at night, and at the same time makes a very reliable fire starter.

Slightly off-topic but here in finland we have daylight around the clock in june/july.

I blissfully overlooked the date of the incident, assuming it to be more recent. Even so, mid afternoon is rather late, except possibly in high latitudes. Of course, practices like this provide lots of opportunities for SAR groups, keeping them active and alert (speaking from experience).

If nothing else, the takeaway is the danger of relying too heavily on a group, or even a guide, to look after you. Too many things can happen, leaving you to look after yourself, at least for a while. Doubly so on the water. Canoedogs' life vest with its well-thought-out extras would have been worth its weight in gold in that situation.

a tiny bit of prep here would at least make the overnight more comfortable:
2 water bottles
rain jacket
tiny sunscreen, bug repellent, chapstick
energy bars
tiny flashlight
matches

in a small backpack or bag.

I will appreciate a link about that vest

Canoedogs' overboard vest thread is here: http://forums.equipped.org/ubbthreads.php?ubb=showflat&Main=10186&Number=115815#Post115815a
Unfortunately a few of the photos have gone missing.

BruceZed did a post in the same vein here: http://forums.equipped.org/ubbthreads.php?ubb=showflat&Number=149609&nt=6&page=1

BTW, the best way to search for stuff in equipped.org forums is Google advanced search: https://www.google.com/advanced_search . It finds pretty much everything.

What type of kayak was the victim paddling? - a "real" kayak with a cockpit and plenty of room for gear, or one of those whoosy "sit on' toys.....

(My opinion is probably showing.)...