How many layers of clothing or blankets should my 3-month-old have at night?

I never seem to have a problem dressing my 3-month-old appropriately for going outside or even just staying around the house all day. However, when it comes to going to bed, I never know what pyjamas to put on her or how many blankets to use. Is there a rule of thumb I can follow for this?

To my knowledge there is no rule of thumb for dressing babies. However, once they pass that newborn period where they really like to be bundled and actually do need more clothes for warmth, you can usually gauge according to your assessment of your environment. If you need an extra blanket at night, your baby probably does as well. We like to avoid a lot of soft bedding, so tuck that blanket in firmly below the baby's shoulders or use a sleeping bag. Infants' hands and feet often do get cold more easily than those of older children and adults, so socks or pyjamas with feet at night is a good idea. Keep in mind that crying is often the way infants communicate, so if your baby cries during the night, feeling too cold or too warm might be the reason.