Bed bugs are much more likely to come out at night. This is because they feed at night, and when you're sleeping in your bed, you supply them with a bountiful diet of human blood. However, looking for them at night is very challenging. Since you won't have any natural light to assist you, your view will be impaired, and the artificial light you'll need to use will scare them away anyway. It makes more sense to wait until the morning and find out if you have a bed bug infestation during the day.
Open up all your shades to let in natural sunlight. This will make looking for the bed bugs easier. Also, turn on all the lights in the room. The more light you have the easier the search will be.
Start with the crevices of your mattress. Use a flashlight, and move the crevices with your hand. If you have a serious bed bug infestation, you will actually see the bugs flattened out and hiding within this crevice.
Inspect all the crevices of your bed frame. Bed bugs also like to hide within your bed frame, keeping them close to their feeding area, which is you. Each crevice is a potential hiding spot, so use the flashlight and look carefully.
Move to the baseboards. You might also find bed bugs flattened out and hiding along your baseboards during the day. In fact, all crevices along your walls are potential hiding spots for these tiny pests.
Look for other signs of bed bugs. In addition to the physical body of the bug, you might find other signs of the infestations. For example, their eggs look like tiny black dots and can be left anywhere the bed bugs might be hiding. Brown spots on the sides of your mattress are the excrement from the bed bugs. Finally, tiny spots of blood on your sheets are from you, leftover from the bed bugs feeding the night before.