extra_night.php

<?php

function countExtraNightBetweenDates(DateTime $begin, DateTime $end, array $extraNightHours): int
{
  $interval = DateInterval::createFromDateString('1 hour');
  $period   = new DatePeriod($begin, $interval, $end);
 
  $extraNightTotal = 0;
  
  foreach($period as $dt) {
    if (in_array((int) $dt->format('H'), $extraNightHours)) {
      $extraNightTotal++;  
    }
  }

  return $extraNightTotal ? ($extraNightTotal - 1) : $extraNightTotal;
}

$extraNightHours = [22, 23, 0, 1, 2, 3, 4, 5];
$begin		 = new DateTime('2019-05-07 23:45:00');
$end		 = new DateTime('2019-05-08 04:30:00');

$extraNightTotal = countExtraNightBetweenDates($begin, $end, $extraNightHours);

var_dump($extraNightTotal);