Low sexual desire is one of the most common sexual health concerns, and it rarely comes down to a single cause. Your body, your mind, your medications, your sleep, and your relationship dynamics all feed into whether you feel like having sex on any given day or week. If your desire has dropped off and you’re wondering why, the answer is usually a combination of factors, many of which are fixable once you identify them.
Stress Changes Your Hormones Directly
When you’re under chronic stress, your body prioritizes survival over reproduction. Your stress response system ramps up cortisol production, and that elevated cortisol actively suppresses the hormonal pathway responsible for sex drive. This isn’t metaphorical. The stress hormone system and the reproductive hormone system are wired to compete with each other: when one goes up, the other goes down.
This suppression lowers testosterone and estrogen output, both of which are essential for desire in all genders. The effect isn’t limited to emotional stress either. Physical stressors like intense exercise without enough calories, overwork, or chronic illness trigger the same hormonal trade-off. If your life has been unusually demanding lately, that alone could explain why sex isn’t on your radar.
Sleep Deprivation Drops Testosterone Fast
Poor sleep is one of the most underestimated libido killers. A study published in JAMA found that just one week of sleeping only five hours per night reduced daytime testosterone levels by 10% to 15% in young, healthy men. That’s a significant drop, equivalent to aging 10 to 15 years in terms of testosterone levels, and it happened in days, not months.
Low testosterone from sleep loss doesn’t just reduce desire. It also causes low energy, poor concentration, and increased sleepiness, all of which make sex feel like a chore rather than something appealing. Women’s hormones are similarly affected by sleep disruption, though the research has focused more heavily on men. If you’re consistently getting less than seven hours, your libido may improve simply by sleeping more.
Antidepressants Are a Major Culprit
If you started an antidepressant and your sex drive vanished, you’re far from alone. Sexual side effects from SSRIs (medications like sertraline, fluoxetine, escitalopram, and paroxetine) affect up to 80% of users. A 2025 study in BMC Psychiatry found that 27% to 65% of women and 26% to 57% of men experienced either new sexual problems or a worsening of existing ones within the first weeks of treatment. When researchers measured more broadly, nearly 89% of women and 85% of men on antidepressants reported some degree of sexual dysfunction.
These medications work by increasing serotonin in the brain, which helps with depression and anxiety but blunts the dopamine and norepinephrine activity that drives sexual arousal and pleasure. The effect can include reduced desire, difficulty becoming aroused, and trouble reaching orgasm. If this sounds familiar, it’s worth knowing that bupropion, a different type of antidepressant, has significantly lower rates of sexual side effects compared to SSRIs. Switching or adding a medication is a conversation worth having with your prescriber.
Hormonal Birth Control Can Lower Desire
Oral contraceptives work partly by suppressing your ovaries’ production of androgens, including testosterone. At the same time, they cause your liver to produce much more of a protein called sex hormone-binding globulin, which binds to testosterone and makes it unavailable to your body. In one study, women who were current long-term users of oral contraceptives had SHBG levels four times higher than women who had never used them (157 vs. 41 nmol/L).
The result is a substantial drop in free testosterone, the form your body actually uses. Since testosterone plays a key role in desire for all genders, this can noticeably dampen libido. What makes this particularly tricky is that SHBG levels may remain elevated even after stopping the pill, meaning the effect on desire can linger. If your libido dropped after starting hormonal contraception, the connection is well-established and worth discussing with your provider.
Your Desire Style Might Be Responsive, Not Broken
Many people assume something is wrong because they never feel a random urge for sex out of nowhere. But sexual desire doesn’t always work that way. Researchers distinguish between two patterns: spontaneous desire, where you feel aroused before any sexual activity begins, and responsive desire, where arousal only kicks in after you’ve already started engaging with sexual cues, touch, or intimacy.
Responsive desire is completely normal and extremely common, particularly among women and people in long-term relationships. If you rarely think about sex unprompted but find yourself enjoying it once things get started, that’s not low libido. It’s a different pathway to the same place. Understanding this can relieve a lot of unnecessary worry and help you and your partner create conditions where desire has a chance to show up, rather than waiting for it to appear on its own.
Thyroid Problems and Iron Deficiency
An underactive thyroid slows down nearly every system in your body, including your sex drive. In one study, 64% of men with hypothyroidism reported low sexual desire. Thyroid disorders affect women at even higher rates than men, and fatigue, weight gain, and mood changes from an underactive thyroid all compound the problem. A simple blood test can identify thyroid issues, and treatment with thyroid hormone typically improves symptoms across the board.
Iron deficiency anemia is another overlooked cause, especially in women with heavy periods. Anemia causes persistent fatigue, anxiety, and reduced physical capacity, all of which dampen desire. Research on reproductive-aged women found that every dimension of sexual function (desire, arousal, lubrication, orgasm, and satisfaction) was significantly lower in women with iron deficiency anemia compared to healthy women. The encouraging finding: after iron treatment, anxiety scores dropped and sexual function scores improved significantly.
Relationship Factors That Erode Desire
Sometimes the issue isn’t in your body at all. Unresolved conflict, feeling emotionally disconnected from your partner, resentment over an unequal division of household responsibilities, or simply the monotony of a long-term routine can all quietly erode desire. For many people, emotional safety and feeling valued are prerequisites for wanting sex, not extras.
Performance anxiety plays a role too. If past sexual experiences have involved pressure, pain, or disappointment, your brain learns to associate sex with stress rather than pleasure. Over time, avoidance becomes automatic. This is particularly common after major life transitions like having a baby, going through menopause, or recovering from illness or surgery, when your body feels unfamiliar and vulnerability feels risky.
When Low Desire Becomes a Clinical Concern
Fluctuations in desire are a normal part of life. But when reduced interest in sex persists for six months or longer and causes you real distress, it may meet the criteria for a clinical diagnosis. The formal criteria require at least three symptoms from a list that includes reduced interest in sexual activity, absent sexual thoughts or fantasies, reduced responsiveness to a partner’s initiation, and diminished pleasure or sensation during sex.
The key word is “distress.” If you have low desire and you’re perfectly fine with it, that’s not a disorder. But if the change is bothering you or affecting your relationship, treatment options exist. For premenopausal women, there is an FDA-approved daily medication that works by shifting the balance of brain chemicals involved in desire, increasing dopamine and norepinephrine while reducing serotonin’s inhibitory effects. It’s taken at bedtime and typically given an eight-week trial. Therapy, particularly approaches that address both psychological and relational factors, is effective for all genders and often the best starting point.
For most people, low desire isn’t a permanent state. It’s a signal. Something in your body, your habits, your medication, or your relationship has shifted, and identifying which factor (or combination of factors) is responsible is the first step toward getting back to a sex life that feels like yours.