using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var sleepSessions = new List<Sleep>{

            new Sleep{StartDate = new DateTime(2022,10,18,22,36,00), EndDate = new DateTime(2022,10,19,07,50,00)},

            new Sleep{StartDate = new DateTime(2022,10,19,15,42,00), EndDate = new DateTime(2022,10,20,07,49,00)},

            new Sleep{StartDate = new DateTime(2022,10,20,22,35,00), EndDate = new DateTime(2022,10,21,06,22,00)},

            new Sleep{StartDate = new DateTime(2022,10,22,00,30,00), EndDate = new DateTime(2022,10,22,08,05,00)}

        };

        TimeSpan earliestSleepTime;

        var multiDaySessions = sleepSessions.Where(x => x.StartDate.Date != x.EndDate.Date).ToList();

        if (multiDaySessions.Any())

        {

            earliestSleepTime = multiDaySessions.Min(x => x.StartDate.TimeOfDay);

        }

        else

        {

            earliestSleepTime = sleepSessions.Min(x => x.StartDate.TimeOfDay);

        }

​

        Console.WriteLine(earliestSleepTime);

    }

    public class  Sleep{

        public DateTime StartDate {get;set;}

        public DateTime EndDate {get;set;}

    }

}