The difference between partners’ chronotypes and preferred time for sex don’t change with relationship length.
Morning males prefer to have sex in earlier hours than evening males.
Male M-types declare that they have the highest desire for sex between 6:00 and 9:00 in the morning, whereas over 70% of evening types would prefer to have sex late in the evening, between 9:00 p.m. and midnight.
An analogical effect is not observed in females, whose most desired time for sex is unrelated to their morningness-eveningness. Both M-type and E-type females prefer to have sex in the evening (although the former prefer to have it before 9:00 p.m., whereas the latter prefer after 9:00 p.m.)
Furthermore, the between-partner difference in preferred time for sex was greater in couples with a more morning-oriented male.
Morning-oriented females are generally more satisfied with their relationship than their evening-oriented ones, whereas in males no association between chronotype and satisfaction is observed.
The main findings of numerous studies show that:
1. similarity in chronotype between partners and female morningness fosters relationship satisfaction in females, but not in males;
2. morningness-eveningness is associated with preferred time for sex in males, but not in females, who in principle prefer evening hours;
3. actual time for sex is up to the female preference; and
4. sexual satisfaction in both genders is associated with lower discrepancy in their preferred time for sex and greater frequency of intercourse.
Index of Sexual Satisfaction (ISS; Hudson et al., 1981).
General relationship satisfaction was measured with the Relationship Assessment Scale (RAS; Hendrick, 1988). This 7-item self-report scale is one of the most commonly used measures in the research of relationship quality