Are mood changes around the menstrual cycle worse during the day?

Mood Changes Around Your Period: Time-of-Day Patterns

Mood changes related to the menstrual cycle follow a distinct temporal pattern, with symptoms worsening progressively throughout the day rather than being worse during daytime hours specifically. The evidence shows that premenstrual mood symptoms typically begin in the late luteal phase (approximately 14 days before menstruation) and reach their lowest point in the 3-5 days immediately before and after menstruation starts 1.

The Temporal Pattern of Premenstrual Mood Changes

Across the Menstrual Cycle

The most robust evidence demonstrates that mood follows a predictable trajectory through the menstrual cycle rather than varying by time of day:

• Well-being peaks during the late follicular phase (mid-cycle, around ovulation) and then progressively declines throughout the entire luteal phase of the cycle 2
• Mood ratings are lowest from 3 days before until 2 days after menstruation, with 54.3% of women with depression experiencing their lowest mean mood scores during this specific window 1
• The decline in mood begins approximately 14 days before menstruation and continues until about 3 days before the next period starts, representing a gradual worsening rather than sudden onset 1

Within-Day Patterns

The available evidence does not support that premenstrual mood changes are specifically worse during daytime hours. Instead:

• Chronotype influences when individuals experience better mood and cognitive function, with morning-types feeling better early in the day and evening-types feeling better later, but this is independent of menstrual cycle effects 3
• Circadian rhythms affect mood timing in general, but the evidence does not demonstrate that premenstrual mood symptoms specifically worsen during daytime versus nighttime hours 3

Clinical Recognition of Premenstrual Dysphoric Disorder

Premenstrual Dysphoric Disorder (PMDD) is characterized by mood symptoms (depressed mood), somatic symptoms (overeating), or cognitive symptoms (forgetfulness) that begin several days before menses, improve within a few days after menses onset, and become minimal or absent within 1 week following menses 3.

Key Diagnostic Features

• Symptoms must show a clear temporal relationship to the menstrual cycle phase rather than time-of-day variation 2
• The pattern involves progressive worsening through the late luteal phase, not diurnal (day-night) fluctuation 1
• Physical distress increases during the second half of the cycle, reaching maximum in the late luteal phase across all severity groups 2

Important Clinical Considerations

Distinguishing Premenstrual Exacerbation from Primary Mood Disorders

• Women with existing depression may experience premenstrual exacerbation (PME), where their baseline depression worsens during the premenstrual phase 4, 1
• At least a subset of women with mood disorders show increased vulnerability during the premenstrual phase for appearance of severe depression or worsening of ongoing depression 4
• The premenstrual phase represents a period of heightened risk rather than a time-of-day vulnerability 4

Physiological Correlates

• Heart rate variability (HRV) tracks with mood changes across the menstrual cycle, showing associations on the same day and 1-3 days prior to mood changes 1
• Sleep architecture changes during the menstrual cycle, with significantly more slow-wave sleep (stage 3+4) in the follicular phase compared to the luteal phase, though this reflects cycle phase rather than time of day 5

Common Pitfalls to Avoid

• Do not confuse circadian rhythm effects with menstrual cycle effects: While chronotype influences when someone feels best during the day, premenstrual mood changes follow the hormonal cycle phases rather than the 24-hour circadian rhythm 3
• Do not overlook premenstrual exacerbation in women with existing mood disorders: The premenstrual phase may unmask or worsen underlying depression that requires different treatment approaches 4
• Do not rely solely on patient recall: Ecological momentary assessment (real-time tracking) over at least two consecutive menstrual cycles provides more accurate characterization of mood patterns than retrospective reporting 1

Treatment Implications

First-line pharmacotherapy for PMDD includes SSRIs such as controlled-release paroxetine (FDA-approved), though paroxetine should be avoided in women who may need tamoxifen 6. Venlafaxine (SNRI) reduces symptom intensity by 40-65% and serves as an alternative when SSRIs are not tolerated 6. Cognitive behavioral therapy reduces the perceived burden of premenstrual symptoms with benefits maintained at 3-month follow-up 6.

The evidence clearly indicates that premenstrual mood changes follow menstrual cycle phases rather than showing specific worsening during daytime hours, with the most severe symptoms occurring in the days immediately before and after menstruation begins 2, 1.