QUESTION: “Dear Ian, I feel terrible. I frequently find myself fantasizing during sex about men other than my husband. Is that abnormal? I feel so guilty, but I can’t help it: Fantasizing helps me enjoy sex, especially after seven years of being together. Sometimes, in the middle of sex, my husband will ask me what I’m thinking about (I guess he can tell I’m in another world), and then I lie and say I’m not thinking about anything. Should I tell him the truth? Won’t he be hurt? I love my husband, but in a weird way, I feel like I’m cheating on him when I fantasize; so much so that I’m starting to avoid sex.”

--Ellen, thirty-six, interior decorator

ANSWER: Relax. You’re not alone. Speaking as a sex therapist and researcher, I can assure you that more than 80 percent of women report that fantasy plays a vital role in enhancing sexual excitement during masturbation or love-making. As a husband, I can also tell you that my wife often has a smile on her face during sex that I’ve come to realize, (and respect), is more about what’s going on in her head than anything to do with me.Studies have shown, time and again, that people fantasize during sex, and not necessarily about the person they’re with. Not only is it normal, it’s healthy. Sexual fantasy, in and of itself, should never be construed as a sign that your relationship is in trouble or that you’re dissatisfied with your partner. Quite the contrary. Sexual fantasy is an indicator that you’re alive and kicking.

Fantasy, a close cousin of dreaming, allows your brain to be stimulated and entertained so your body can relax. As neuroscientist Mark Solms, a leading expert in the field of sleep-research, explains: “[D]reaming does for the brain what Saturday-morning cartoons do for the kids: It keeps them sufficiently entertained so that the serious players in the household can get needed recovery time. Without such diversion, the brain would be urging us up and out into the world to keep it fully engaged.”

Fantasies, much like dreams, free your brain to explore secret, extraordinary realms without the compunction of practicality, morality, or logic. Flooded by a barrage of images, memories, and thoughts, your body can, basically, kick back and enjoy the show. Trying to block, censor, or edit those images, on the other hand, can lead to self-consciousness and inhibition, or even preclude orgasm altogether.

More importantly, fantasy also helps your mind to shut down, an important component of the female orgasm. A recent study in which male and female brains were scanned during sexual arousal revealed that women virtually fall into a ‘trance’ during orgasm, and that this brain “de-activity” is necessary to female orgasm. The scans showed that in the female orgasm, activity is reduced across all the brain regions--conscious and subconscious. It’s my personal opinion that the female penchant to fantasize during sex enables the parts of her brain responsible for processing fear, anxiety, and emotion to relax and reduce activity. A big part of female arousal, much more so than men, seems to be deep relaxation and a lack of anxiety. Fantasy helps that happen. Says Dr. Gert Holstege of the University of Groningen in the Netherlands, “What this means is that deactivation, letting go of all fear and anxiety, might be the most important thing, even necessary, to have an orgasm.”

So keep fantasizing. Your body and mind are doing what comes naturally in order for you to experience orgasm. Every woman deserves to have a smile on her face during sex.