It's actually a pretty primal thing: "When people have sex they're usually having skin-to-skin contact, and this kind of contact is the first primal way we as humans get comforted [as babies with our mothers]," Cooper explained.
"Sexual connection give partners loads of skin-to-skin caressing and touch, and can help to regulate one another's moods," the therapist added.
While lack of sex won't lead to depression, it will definitely leave you feeling blue.
This isn't all the bad news.
2. Weakened vaginal walls
For women, lack of sex can also lead to weakened vaginal walls and the result is usually painful sexual relations (when you do eventually get back into it).
The vagina will also have some trouble lubricating if you haven't had sex in a while - and this is a common side-effect for older women in particular, due to a lack of oestrogen.
"If you take a young woman who's 20 or 30 years old she's going to have plenty of oestrogen around to make sure those tissues stay healthy, elastic and lubricated when she's not having sex," Lauren Streicher, MD, said, quoted by The Sun.
3. More cramps and more period pains
Less sex can also mean worse period pains.
"The uterus is a muscle and many women will actually have a uterine contraction when they orgasm, which will cause the blood to expel more quickly, which will in turn decrease menstrual cramps," Dr Streicher said.
"Also, there may be an increase in endorphins, which also will help with menstrual cramps."
4. More stress
Sex is a good way to get rid of some stress and, just like having sex can de-stress you, not having sex can bring on more stress.
5. Less UTIs
Finally some positive effects. You're less likely to develop a urinary tract infection (UTI).
"Frequency of sexual intercourse is the strongest predictor of recurrent urinary tract infections," the journal American Family Physician says.
