During the heat cycle bitches experience a flurry of hormonal changes similar to those experienced by female humans. Some of these changes are visible while others are not. Your dog may also be affected physically or mentally. Stress anxiety or fatigue are common symptoms. Your dog may also display aggressive behavior.
In order to calm your French bulldog down during her season you should give her extra attention. She might need a bit more petting than usual to feel cared for. To help her sleep better you can also engage her in more physical activities. Consider shortening her exercise period if her walks tend to aggravate her. She can also be kept indoors depending on what she is doing while she is in heat. To assist her mentally you should also provide her with interactive toys. Most importantly try to create a calm environment in your house. This should make her feel better.