Nighttime whitening involves using whitening trays or strips while sleeping for convenience and effectiveness. This method allows the whitening gel to work overnight, often yielding better results. Clients should be informed about the benefits of nighttime whitening, especially if they have a busy daytime schedule. This tip is particularly helpful for clients looking for an efficient way to maintain their whitening results. Providing this information ensures that clients can integrate whitening into their routine seamlessly, maximizing results with minimal effort.