After 7 passages to Hawaii with WILDFLOWER, my old school take is a little different. With a balanced boat, easily shifted sailplan, confidence in AP/Windvane, and plenty of practice, sleep was not a major issue in the SHTP.
I always got more rest in the SHTP than was ever possible in DH PacCups, where we would hand steer the whole way. Being rested is the key to good decision making.
In the 1978 SHTP, WILDFLOWER's self steering was a Sail-O-Mat windvane and two TillerMaster AP's. I arrived in Hanalei with half a windvane, and one Tillermaster.
In the 2008 SHTP WILDFLOWER had a newer Sail-O-Mat windvane, an Auto-Helm 1000 and 2000 tiller pilots, and the old TillerMaster.
In the SHTP, on my 27', 6,500 pound displacement hull, I would predominantly handsteer in light air, when full time attention was needed to sail trim and windshifts. Handsteering in a tradewind breeze, sitting in a beanbag, with a cockpit awning for sun relief, when surfing waves, was great fun. The small cockpit awning was a blessing, and could be adjusted fore and aft, and angled for best effect.
Handsteering in squalls is often the safest thing to do if you don't want to reduce, then reset sail for the 15 minutes the squall is passing.
Before AIS, I would run my radar at night when napping. The radar would pick up the rain in squalls on the darkest nights. But the Furuno internal alarm was barely audible at sea. I made an external alarm on a long cord I wore around my neck when napping. Along with my egg timer.
In 2008 I unplugged the radar and used a standalone NASA AIS that had a louder alarm, but still not loud enough. Again I rigged an external alarm to hang around my neck.
LIGHTSPEED is correct: the need to pee awakens on a fairly reliable schedule. Rather than stressing over sleep schedules, the boat will tell you when it needs you on deck. And your body will tell you when it needs rest.
Getting rest in the SHTP just happens. Everybody has a different boat, different physical rhythms. Being in tune with the boat, and being prepared and having things rigged to be safe, and to lose minimum speed when needing to be "off watch" is the ticket.