Feeling sleepy in the afternoons is a common problem for many people. It is rarely a sign of a serious medical problem, fortunately. The doctors who will be well qualified to discuss this issue with you include your primary care doctor
. Cold weather is very unlikely to provoke sleepiness. In fact the fact that you say the sleepiness occurs in the early afternoon suggests that the problem is in fact something else. Feeling tired after lunch is related to digestion; rising insulin in the blood, which manages sugar levels and diversion of blood from your brain to your intestines to aid in the digestion are the main culprits. To deal with these effects it is helpful to eat smaller meals at lunch and meals higher in protein and lower in processed foods and carbohydrates and to avoid sugary beverages. It can also be helpful to perform some exercise. The fact that you do not have these symptoms when you work from home suggests that your eating and exercise routine there is different than in the office. As always the diagnosis and the management of your particular concern will require a physical examination by your personal physician. Setting up an office visit with your primary care doctor might be advised.