Leave a cup of water on the nightstand before you go to sleep every night.
The subject told me that both her mother and her neighbor leave a cup of water on the nightstand before they go to sleep every night. The idea behind this is that the ancestors come to drink the water. The subject said that she has heard of a couple of people doing it, but does not know where it exactly comes from, she refers to the Day of the Dead celebration that occurs in early November, in which the entire neighborhood travels to the cemetery to bring food and drink offerings to the dead. She says that taking care of their ancestors is a big part of Mexican culture.
I think that this custom reflects the idea of taking care of and looking after the dead, much like the Day of the Dead celebration. I think that leaving the water out at night shows the ancestors that the people have not forgotten about them, it shows that there is still the respect there. Leaving water is also a part of the Day of the Dead celebration, and when I asked the subject about this she said that its the only drink the ancestors drink. She said that everyone brings water for the dead. The fact that her mother and her neighbor do it every night shows their dedication to this custom. I asked the subject if she continued the custom since she lives alone now, and she said no. She said that her mother moved here from Mexico, so she continues a lot more of the traditional beliefs, while the subject does not. This is known as acculturation and assimilation. The subject, being a second-generation immigrant, has taken on more elements of the American culture, and lost some of the traditional Mexican ones.