How to update tkinter window every 4 seconds?

I am trying to create a program that reads lines from a file and puts them into a tkinter window. At the moment my code is this:

def read_notifications():
    #def update():
    #   window.config(text=str(random.random()))
    #   window.after(1000, update)
    aaa = 1
    while True:
        re = open("Y:/System Info/notifications.txt", "r")
        rf = re.read()
        rh = rf.count("\n")
        re.close()
        lines = [line.rstrip('\n') for line in open("Y:/System Info/notifications.txt")]
        rk = -1
        while True:
            aaa = aaa + 2
            rk = rk + 1
            #print(lines[rk])
            rl = rk + 1
            ya = lines[rk].split("#")
            yb = str(tomrt)
            if ya[1] == yb:
                yc = "Tommorow"
            else:
                if ya[1] == "0":
                    yc = "Monday"
                if ya[1] == "1":
                    yc = "Tuesday"
                if ya[1] == "2":
                    yc = "Wednesday"
                if ya[1] == "3":
                    yc = "Thursday"
                if ya[1] == "4":
                    yc = "Friday"
                if ya[1] == "5":
                    yc = "Saturday"
                if ya[1] == "6":
                    yc = "Sunday"       
            c = 650
            window = tk.Tk()
            #back = tk.Frame(width=700, height=c)
            #back.pack()
            window.title("Notifications")
            window.iconbitmap("1235.ico")
            #Subject
            lbl = tk.Label(window, text=ya[0])
            lbl.config(font=("Courier", 18))
            lbl.grid(column=0, row=0)
            #lbl.pack(side=tk.LEFT,)
            #Day
            lbl = tk.Label(window, text=" " + yc)
            lbl.config(font=("Courier", 16))
            lbl.grid(column=2, row=0)
            #Type
            lbl = tk.Label(window, text=ya[2])
            lbl.config(font=("Courier", 16))
            lbl.grid(column=4, row=0)
            #Descripion
            lbl = tk.Label(window, text=ya[4])
            lbl.config(font=("Courier", 16))
            lbl.grid(column=6, row=0)
            #lbl.pack(side=tk.LEFT)
            #window.after(1000, update)
            if rl == rh:
                print("hello")
                break
        if aaa > 2:
            time.sleep(4)
            window.destroy()
        else:
            window.mainloop()

I am not sure why this doesn't work properly. I am trying to make it so the tkinter window will update itself every 4 seconds, as another program is making changes to the notifications.txt file and I want the tkinter windows to update accordingly.