How old is your DS? I always dressed my babies in an extra layer to what I was in. And I found a room thermometer invaluable because its really hard to guess just going on the outside temperature. My daughters room was dropping down to 13 degrees (not in summer though) so I had to get a heater for her room as the rest of the house was much warmer. Might be worth investing in one. Or a cotton blanket that can be tucked right in tight.